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Information on EC 2.4.1.21 - starch synthase (glycosyl-transferring) and Organism(s) Arabidopsis thaliana and UniProt Accession F4IAG2
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2.4.1.21 starch synthase (glycosyl-transferring)IUBMB Comments
The accepted name varies according to the source of the enzyme and the nature of its synthetic product, e.g. starch synthase, bacterial glycogen synthase. Similar to EC 2.4.1.11 [glycogen(starch) synthase] but the preferred or mandatory nucleoside diphosphate sugar substrate is ADP-alpha-D-glucose. The entry covers starch and glycogen synthases utilizing ADP-alpha-D-glucose.
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Word Map
- 2.4.1.21
- amylose
- grain
- amylopectin
- endosperm
-
pyrophosphorylase
- maize
- wheat
- potato
-
waxy
- glucans
- japonica
-
debranching
- amyloplasts
- triticum
- aestivum
- indica
- agpase
- kernel
-
chain-length
- isoamylase
- adpglucose
- sbeiib
-
starch-branching
-
homoeologous
-
starch-binding
- alpha-glucans
-
2.7.7.27
-
diphosphate-glucose
- pullulanase
-
high-amylose
-
hexaploid
- adp-glc
-
amylose-free
-
spikelet
-
grain-filling
- biofuel production
- food industry
- nutrition
- agriculture
-
chalky
The taxonomic range for the selected organisms is: Arabidopsis thaliana
The expected taxonomic range for this enzyme is: Bacteria, Eukaryota, Archaea
The expected taxonomic range for this enzyme is: Bacteria, Eukaryota, Archaea
Reaction Schemes
Synonyms
starch synthase, ssiia, gsase, ssiii, granule-bound starch synthase i, ssiiia, starch synthase iia, starch synthetase, starch synthase iii, starch synthase ii, 
more
topSYNONYM 
ORGANISM
UNIPROT
COMMENTARY 
LITERATURE
adenosine diphosphate glucose-starch glucosyltransferase
-
-
-
-
adenosine diphosphoglucose-starch glucosyltransferase
-
-
-
-
ADP-glucose starch synthase
-
-
-
-
ADP-glucose synthase
-
-
-
-
ADP-glucose transglucosylase
-
-
-
-
ADP-glucose-starch glucosyltransferase
-
-
-
-
ADPG starch synthetase
-
-
-
-
ADPG-starch glucosyltransferase
-
-
-
-
glucosyltransferase, adenosine diphosphoglucose-starch
-
-
-
-
SSI
SSIII
starch synthetase
-
-
-
-
REACTION TYPE
ORGANISM
UNIPROT
COMMENTARY
LITERATURE
hexosyl group transfer
-
-
-
-
PATHWAY SOURCE
PATHWAYS
BRENDA
-
-, -
SYSTEMATIC NAME
IUBMB Comments
ADP-glucose:(1->4)-alpha-D-glucan 4-alpha-D-glucosyltransferase
The accepted name varies according to the source of the enzyme and the nature of its synthetic product, e.g. starch synthase, bacterial glycogen synthase. Similar to EC 2.4.1.11 [glycogen(starch) synthase] but the preferred or mandatory nucleoside diphosphate sugar substrate is ADP-alpha-D-glucose. The entry covers starch and glycogen synthases utilizing ADP-alpha-D-glucose.
CAS REGISTRY NUMBER
COMMENTARY
9030-10-8
-
SUBSTRATE
PRODUCT
REACTION DIAGRAM
ORGANISM
UNIPROT
COMMENTARY
(Substrate)
(Substrate)
LITERATURE
(Substrate)
(Substrate)
COMMENTARY
(Product)
(Product)
LITERATURE
(Product)
(Product)
Reversibility
r=reversible
ir=irreversible
?=not specified
r=reversible
ir=irreversible
?=not specified
UDP-glucose + (1,4-alpha-D-glucosyl)n
UDP + (1,4-alpha-D-glucosyl)n+1
SSIII uses preferentially ADP-glucose, although UDP-glucose can also be used as a sugar donor substrate
-
-
?
ADP-alpha-D-glucose + glycogen
ADP + ?
187% activity compared to maltotriose
-
-
?
ADP-alpha-D-glucose + maltoheptaose
ADP + maltooctaose
80% activity compared to maltotriose
-
-
?
ADP-alpha-D-glucose + maltooctaose
ADP + maltononaose
79% activity compared to maltotriose
-
-
?
ADP-alpha-D-glucose + maltopentaose
ADP + maltohexaose
116% activity compared to maltotriose
-
-
?
ADP-alpha-D-glucose + maltose
ADP + ?
20% activity compared to maltotriose
-
-
?
ADP-alpha-D-glucose + maltose
ADP + maltotriose
20% activity compared to maltotriose
-
-
?
ADP-alpha-D-glucose + maltotetraose
ADP + maltopentaose
103% activity compared to maltotriose
-
-
?
ADP-alpha-D-glucose + maltotriose
ADP + maltotetraose
100% activity
-
-
?
ADP-glucose + (1,4-alpha-D-glucosyl)n
ADP + (1,4-alpha-D-glucosyl)n+1
-
SSIII is able to partially function in production of DP12 to DP25 chains. SSIII is not required for the normal population of these chains
-
-
?
ADP-glucose + (1,4-alpha-glucosyl)n
ADP + (1,4-alpha-glucosyl)n+1
-
function of SSI is mainly involved in the synthesis of small outer chains during amylopectin cluster synthesis
-
-
?
ADP-glucose + alpha-1,4-polyglucan
ADP + alpha-1,4-polyglucan
-
two insertion mutations at the AtSS3 gene locus, termed Atss3-1 and Atss3-2, condition complete loss of SSIII activity and prevent normal gene expression at both the mRNA and protein levels. Total SS activity is increased in both Atss3 mutants and a specific SS activity appears to be upregulated. In addition to its expected direct role in starch assembly, SSIII also has a negative regulatory function in the biosynthesis of transient starch in Arabidopsis
-
-
?
ADP-glucose + (1,4-alpha-D-glucosyl)n
ADP + (1,4-alpha-D-glucosyl)n+1
recombinant SSIII-CD uses with more efficiency rabbit muscle glycogen than amylopectin as primer and displays a high apparent affinity for ADP-Glc
-
-
?
ADP-glucose + (1,4-alpha-D-glucosyl)n
ADP + (1,4-alpha-D-glucosyl)n+1
SSIII uses preferentially ADP-glucose, although UDP-glucose can also be used as a sugar donor substrate. the N-terminal starch-binding domains have a regulatory role, showing a starch binding capacity and modulating the catalytic properties of SSIII
-
-
?
ADP-alpha-D-glucose + maltohexaose
ADP + maltoheptaose
90% activity compared to maltotriose
-
-
?
ADP-alpha-D-glucose + [(1->4)-alpha-D-glucosyl]n
ADP + [(1->4)-alpha-D-glucosyl]n+1
-
-
-
-
?
ADP-alpha-D-glucose + [(1->4)-alpha-D-glucosyl]n
ADP + [(1->4)-alpha-D-glucosyl]n+1
-
-
-
?
additional information
?
-
less than 1% activity with D-glucose
-
-
?
additional information
?
-
-
the starch binding domains of starch synthase III bind preferentially to cell wall polysaccharides like cellulose, xylan and pectin rather than to starch
-
-
-
NATURAL SUBSTRATE
NATURAL PRODUCT
REACTION DIAGRAM
ORGANISM
UNIPROT
COMMENTARY
(Substrate)
(Substrate)
LITERATURE
(Substrate)
(Substrate)
COMMENTARY
(Product)
(Product)
LITERATURE
(Product)
(Product)
REVERSIBILITY
r=reversible
ir=irreversible
?=not specified
r=reversible
ir=irreversible
?=not specified
ADP-glucose + (1,4-alpha-D-glucosyl)n
ADP + (1,4-alpha-D-glucosyl)n+1
-
SSIII is able to partially function in production of DP12 to DP25 chains. SSIII is not required for the normal population of these chains
-
-
?
ADP-glucose + (1,4-alpha-glucosyl)n
ADP + (1,4-alpha-glucosyl)n+1
-
function of SSI is mainly involved in the synthesis of small outer chains during amylopectin cluster synthesis
-
-
?
ADP-glucose + alpha-1,4-polyglucan
ADP + alpha-1,4-polyglucan
-
two insertion mutations at the AtSS3 gene locus, termed Atss3-1 and Atss3-2, condition complete loss of SSIII activity and prevent normal gene expression at both the mRNA and protein levels. Total SS activity is increased in both Atss3 mutants and a specific SS activity appears to be upregulated. In addition to its expected direct role in starch assembly, SSIII also has a negative regulatory function in the biosynthesis of transient starch in Arabidopsis
-
-
?
ADP-alpha-D-glucose + [(1->4)-alpha-D-glucosyl]n
ADP + [(1->4)-alpha-D-glucosyl]n+1
-
-
-
-
?
ADP-alpha-D-glucose + [(1->4)-alpha-D-glucosyl]n
ADP + [(1->4)-alpha-D-glucosyl]n+1
-
-
-
?
INHIBITOR
ORGANISM
UNIPROT
COMMENTARY
LITERATURE
IMAGE
ACTIVATING COMPOUND
ORGANISM
UNIPROT
COMMENTARY
LITERATURE
IMAGE
KM VALUE [mM]
SUBSTRATE
ORGANISM
UNIPROT
COMMENTARY
LITERATURE
IMAGE
0.59
ADP-glucose
-
catalytic domain co-expressed with starch-binding domain 3 and large part of starch-binding domain 2
0.62
ADP-glucose
-
catalytic domain co-expressed with starch-binding domains 23
0.81
ADP-glucose
-
catalytic domain co-expressed with starch-binding domain 2 and part of starch-binding domain 3
0.95
ADP-glucose
-
catalytic domain co-expressed with starch-binding domains 123
1.68
ADP-glucose
-
truncated protein lacking starch binding domain 1 and large part of starch binding domain 2
1.77
ADP-glucose
-
truncated protein lacking starch binding domain 1 and medium part of starch binding domain 2
2.39
ADP-glucose
-
truncated protein lacking starch binding domain 1 and small part of starch binding domain 2
ORGANISM
COMMENTARY
LITERATURE
UNIPROT
SEQUENCE DB
SOURCE
SOURCE TISSUE
ORGANISM
UNIPROT
COMMENTARY
LITERATURE
SOURCE
LOCALIZATION
ORGANISM
UNIPROT
COMMENTARY
GeneOntology No.
LITERATURE
SOURCE
GENERAL INFORMATION
ORGANISM
UNIPROT
COMMENTARY
LITERATURE
malfunction
metabolism
physiological function
malfunction
-
Arabidopsis thaliana mutants lacking the SS4 isoform of starch synthase have strongly reduced numbers of starch granules per chloroplast
malfunction
-
a mutant lacking starch synthase 4 is impaired in its ability to initiate starch granules, its chloroplasts rarely contain more than one large granule, and the plants have a pale appearance and reduced growth. The chloroplastic alpha-amylase AMY3 abundance is reduced in mutants lacking starch synthase 3 and/or 4
malfunction
-
mutants lacking starch synthase 4 reveal a strongly reduced granule number per chloroplast
metabolism
-
isoform SS4 interacts with the proteins fibrillin 1a and 1b, which are mainly located in plastoglobules
metabolism
-
the enzyme plays a key role in granule initiation, allowing it to proceed in a way that avoids premature degradation of primers by starch hydrolases, such as the chloroplastic alpha-amylase AMY3
physiological function
-
function of isoform SSIV in the priming process of starch granule formation. SSIV is necessary and sufficient to establish the correct number of starch granules observed in wild-type chloroplasts. The role of SSIV in granule seeding can be replaced, in part, by SSIII. The simultaneous elimination of both proteins prevents Arabidopsis thaliana from synthesizing starch. The soluble starch synthase activity in ssI ssII ssIV mutant plants is 32% of the activity determined in wild-type plants, whereas no soluble SS activity can be detected in ssI ssII ssIII mutant plants
physiological function
-
construction of double mutant isoforms ss1- ss2- or ss1- ss3- lines using confirmed null mutations. Double mutant plants develop similarly to the wild type, although they accumulate less leaf starch in both short-day and long-day diurnal cycles. Lines containing only SS2 and SS4, or SS3 and SS4, are able to produce substantial amounts of starch granules. In both double mutants the residual starch is structurally modified including higher ratios of amylose to amylopectin, altered glucan chain length distribution within amylopectin, abnormal granule morphology, and altered placement of alpha(1-6) branch linkages relative to the reducing end of each linear chain. Starch Ssynthase activity affects not only chain elongation but also the net result of branch placement accomplished by the balanced activities of starch branching enzymes and starch debranching enzymes. Isoform SS3 partially overlaps in function with isoform SS1 for the generation of short glucan chains within amylopectin
physiological function
-
isoform starch synthase 4 is essential for coordination of starch granule formation with chloroplast division during Arabidopsis leaf expansion
physiological function
-
starch synthase 4 is involved in the process of starch granule formation in leaves
UNIPROT
ENTRY NAME
ORGANISM
NO. OF AA
NO. OF TRANSM. HELICES
MOLECULAR WEIGHT[Da]
SOURCE
SEQUENCE
LOCALIZATION PREDICTION
The reliability class of the localization prediction ranges from 1 (very reliable) to 5 (not reliable).
The reliability class of the localization prediction ranges from 1 (very reliable) to 5 (not reliable). SSY3_ARATH
1042
0
118512
Swiss-Prot
Mitochondrion (Reliability: 5)
SUBUNIT
ORGANISM
UNIPROT
COMMENTARY
LITERATURE
additional information
-
enzyme contains an N-terminal region, including three in-tandem starch-binding domains, followed by a C-terminal catalytic domain. The D(316-344) and D(495-535) regions in the D2 and D3 domains, respectively, but not the individual starch-binding domains, are involved in the interaction with the catalytic domain. Residues W366 and Y394 in the D2 domain are important in starch binding. Residue W366 is key to the apparent affinity for the polysaccharide substrate of starch synthase III
CRYSTALLIZATION (Commentary)
ORGANISM
UNIPROT
LITERATURE
catalytic domain bound to ADP and inhibitor acarbose, hanging drop vapor diffusion method, using 0.2 MLi2SO4, 0.1MBis-Tris pH 5.5, 25% (w/v) PEG3350
PROTEIN VARIANTS
ORGANISM
UNIPROT
COMMENTARY
LITERATURE
C164S
C164S/C265S
the mutant shows strongly reduced activity compared to the wild type enzyme
C164S/C545S
C261S
the mutant shows reduced activity compared to the wild type enzyme
C265S
C265S/C545S
C442S
the mutant shows reduced activity compared to the wild type enzyme
C458S
the mutant shows reduced activity compared to the wild type enzyme
C545S
W366A
-
mutation in starch-binding domains, 3fold decrease in affinity to starch
W366A/Y394A
-
mutation in starch-binding domains, significant decrease in affinity to starch
Y394A
-
mutation in starch-binding domains, 2fold decrease in affinity to starch
C164S
the mutant shows reduced activity compared to the wild type enzyme
C164S
the mutant shows 50% activity compared to the wild type enzyme
C164S/C545S
the mutant shows strongly reduced activity compared to the wild type enzyme
C164S/C545S
the double mutant with 13% of wild type activity has considerably decreased redox sensitivity as compared to wild type enzyme (30% vs 77%)
C265S
the mutant shows reduced activity compared to the wild type enzyme
C265S
the mutant shows 37% activity compared to the wild type enzyme
C265S/C545S
the mutant shows strongly reduced activity compared to the wild type enzyme
C265S/C545S
the mutant shows 8% activity compared to the wild type enzyme
C545S
the mutant shows 27% activity compared to the wild type enzyme
C545S
the mutant shows strongly reduced activity compared to the wild type enzyme
PURIFICATION (Commentary)
ORGANISM
UNIPROT
LITERATURE
CLONED (Commentary)
ORGANISM
UNIPROT
LITERATURE
construction of recombinant full length and truncated isoforms of SSIII, lacking one, two, or three starch-binding domains, and recombinant proteins, containing three, two, or one starch-binding domains, to investigate the role of these domains in enzyme activity
the catalytic C-terminal domain (SSIII-CD) of is cloned and expressed in Escherichia coli. SSIII-CD fully complements the production of glycogen by an Agrobacterium tumefaciens glycogen synthase null mutant, suggesting that this truncated isoform restores in vivo de novo synthesis of bacterial glycogen
EXPRESSION
ORGANISM
UNIPROT
LITERATURE
the enzyme is in the reduced and active form during the day with active photosynthesis
APPLICATION
ORGANISM
UNIPROT
COMMENTARY
LITERATURE
biofuel production
-
transgenic Arabidopsis plants overexpressing the starch binding domains of starch synthase III have an advantage for the production of bioethanol in terms of saccharification of essential substrates
REF.
AUTHORS
TITLE
JOURNAL
VOL.
PAGES
YEAR
ORGANISM (UNIPROT)
PUBMED ID
SOURCE
Zhang, X.; Myers, A.M.; James, M.G.
Mutations affecting starch synthase III in Arabidopsis alter leaf starch structure and increase the rate of starch synthesis
Plant Physiol.
138
663-674
2005
Arabidopsis thaliana
Delvalle, D.; Dumez, S.; Wattebled, F.; Roldan, I.; Planchot, V.; Berbezy, P.; Colonna, P.; Vyas, D.; Chatterjee, M.; Ball, S.; Merida, A.; DHulst, C.
Soluble starch synthase I: a major determinant for the synthesis of amylopectin in Arabidopsis thaliana leaves
Plant J.
43
398-412
2005
Arabidopsis thaliana
Palopoli, N.; Busi, M.V.; Fornasari, M.S.; Gomez-Casati, D.; Ugalde, R.; Parisi, G.
Starch-synthase III family encodes a tandem of three starch-binding domains
Proteins
65
27-31
2006
Arabidopsis thaliana
Valdez, H.A.; Busi, M.V.; Wayllace, N.Z.; Parisi, G.; Ugalde, R.A.; Gomez-Casati, D.F.
Role of the N-terminal starch-binding domains in the kinetic properties of starch synthase III from Arabidopsis thaliana
Biochemistry
47
3026-3032
2008
Arabidopsis thaliana (F4IAG2), Arabidopsis thaliana
Zhang, X.; Szydlowski, N.; Delvalle, D.; DHulst, C.; James, M.G.; Myers, A.M.
Overlapping functions of the starch synthases SSII and SSIII in amylopectin biosynthesis in Arabidopsis
BMC Plant Biol.
8
96
2008
Arabidopsis thaliana, Arabidopsis sp.
Busi, M.V.; Palopoli, N.; Valdez, H.A.; Fornasari, M.S.; Wayllace, N.Z.; Gomez-Casati, D.F.; Parisi, G.; Ugalde, R.A.
Functional and structural characterization of the catalytic domain of the starch synthase III from Arabidopsis thaliana
Proteins
70
31-40
2008
Arabidopsis thaliana (F4IAG2), Arabidopsis thaliana
Wayllace, N.Z.; Valdez, H.A.; Ugalde, R.A.; Busi, M.V.; Gomez-Casati, D.F.
The starch-binding capacity of the noncatalytic SBD2 region and the interaction between the N- and C-terminal domains are involved in the modulation of the activity of starch synthase III from Arabidopsis thaliana
FEBS J.
277
428-440
2010
Arabidopsis thaliana
Szydlowski, N.; Ragel, P.; Raynaud, S.; Lucas, M.M.; Roldan, I.; Montero, M.; Munoz, F.J.; Ovecka, M.; Bahaji, A.; Planchot, V.; Pozueta-Romero, J.; DHulst, C.; Merida, A.
Starch granule initiation in Arabidopsis requires the presence of either class IV or class III starch synthases
Plant Cell
21
2443-2457
2009
Arabidopsis thaliana
Szydlowski, N.; Ragel, P.; Hennen-Bierwagen, T.A.; Planchot, V.; Myers, A.M.; Merida, A.; dHulst, C.; Wattebled, F.
Integrated functions among multiple starch synthases determine both amylopectin chain length and branch linkage location in Arabidopsis leaf starch
J. Exp. Bot.
62
4547-4559
2011
Arabidopsis thaliana
Crumpton-Taylor, M.; Pike, M.; Lu, K.J.; Hylton, C.M.; Feil, R.; Eicke, S.; Lunn, J.E.; Zeeman, S.C.; Smith, A.M.
Starch synthase 4 is essential for coordination of starch granule formation with chloroplast division during Arabidopsis leaf expansion
New Phytol.
200
1064-1075
2013
Arabidopsis thaliana
Gamez-Arjona, F.M.; Raynaud, S.; Ragel, P.; Merida, A.
Starch synthase 4 is located in the thylakoid membrane and interacts with plastoglobule-associated proteins in Arabidopsis
Plant J.
80
305-316
2014
Arabidopsis thaliana
Skryhan, K.; Cuesta-Seijo, J.A.; Nielsen, M.M.; Marri, L.; Mellor, S.B.; Glaring, M.A.; Jensen, P.E.; Palcic, M.M.; Blennow, A.
The role of cysteine residues in redox regulation and protein stability of Arabidopsis thaliana starch synthase 1
PLoS ONE
10
e0136997
2015
Arabidopsis thaliana, Arabidopsis thaliana (Q9FNF2)
Brust, H.; Lehmann, T.; DHulst, C.; Fettke, J.
Analysis of the functional interaction of Arabidopsis starch synthase and branching enzyme isoforms reveals that the cooperative action of SSI and BEs results in glucans with polymodal chain length distribution similar to amylopectin
PLoS ONE
9
e102364
2014
Arabidopsis thaliana
Nielsen, M.M.; Ruzanski, C.; Krucewicz, K.; Striebeck, A.; Cenci, U.; Ball, S.G.; Palcic, M.M.; Cuesta-Seijo, J.A.
Crystal structures of the catalytic domain of Arabidopsis thaliana starch synthase IV, of granule bound starch synthase from CLg1 and of granule bound starch synthase I of Cyanophora paradoxa illustrate substrate recognition in starch synthases
Front. Plant Sci.
9
1138
2018
Arabidopsis thaliana (Q0WVX5), Arabidopsis thaliana, Cyanobacterium sp. CLg1 (V5SNJ5)
Raynaud, S.; Ragel, P.; Rojas, T.; Merida, A.
The N-terminal part of Arabidopsis thaliana starch synthase 4 determines the localization and activity of the enzyme
J. Biol. Chem.
291
10759-10771
2016
Arabidopsis thaliana
Seung, D.; Lu, K.J.; Stettler, M.; Streb, S.; Zeeman, S.C.
Degradation of glucan primers in the absence of starch synthase 4 disrupts starch granule initiation in Arabidopsis
J. Biol. Chem.
291
20718-20728
2016
Arabidopsis thaliana
Grisolia, M.J.; Peralta, D.A.; Valdez, H.A.; Barchiesi, J.; Gomez-Casati, D.F.; Busi, M.V.
The targeting of starch binding domains from starch synthase III to the cell wall alters cell wall composition and properties
Plant Mol. Biol.
93
121-135
2017
Arabidopsis thaliana
Malinova, I.; Alseekh, S.; Feil, R.; Fernie, A.R.; Baumann, O.; Schoettler, M.A.; Lunn, J.E.; Fettke, J.
Starch synthase 4 and plastidal phosphorylase differentially affect starch granule number and morphology
Plant Physiol.
174
73-85
2017
Arabidopsis thaliana
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