1.3.99.4 evolution 3-oxosteroid DELTA1-dehydrogenases are found in a large variety of microorganisms, especially in bacteria belonging to the phylum Actinobacteria 763443 1.3.99.4 evolution the genome of Rhodocccus ruber Chol-4 contains three genes that encode for 3-ketosteroid DELTA1-dehydrogenases: KstD1, KstD2 and KstD3. Their gene nucleotide sequences are similar to reciprocal homologues in other rhodococci. Physiological studies on strain Cho-4 and its kstD-deleted mutants demonstrate that the three dehydrogenases are involved in the catabolism of cholesterol at different degrees depending on catabolic intermediates. These KstDs are distinguished by their substrate profiles comprising C-19 and C-22 3-ketosteroids. Particularly, KstD3 has a preference for 5alpha-3-oxosteroids 763042 1.3.99.4 malfunction all ksdD-overexpressing strains (isozymes KsdD1-5) not only exhibit a faster initial conversion rate (increased by 22-102%) but also achieve a higher conversion ratio (increased by 15-66%) than that of the control strain during the conversion of 4-androstene-3,17-dione to 1,4-androstadiene-3,17-dione. Apparently, KsdD3 and KsdD2 have more effect on DELTA1-dehydrogenation -, 763180 1.3.99.4 malfunction an enzyme-deficient mutant strain is unable to use cholesterol as a source of carbon and energy and has a limited ability to multiply. The mutant is unable to inhibit the NO and reactive oxygen species production induced through Toll-like receptor 2 signaling in infected resting macrophages, phenotpe, overview -, 724670 1.3.99.4 metabolism oxosteroid-DELTA1-dehydrogenase (KstD) is a key enzyme in the metabolic pathway for chemical modifications of steroid hormones, overview of proposed pathway for phytosterols degradation in mycobacteria -, 763441 1.3.99.4 metabolism the 3-ketosteroid-DELTA1-dehydrogenase is involved in steroid metabolism catalyzing the transformation of 4-androstene-3,17-dione to androst-1,4-diene-3,17-dione specifically -, 725830 1.3.99.4 additional information enzyme residues Y125, Y365, and Y541 are essential to the function of KsdD, residues Y122, S138, and E140 contribute to the catalysis of KsdD, modelling of the enzyme-substrate bindung structure, overview -, 763772 1.3.99.4 additional information homology-based structural analysis and structure modeling of KstD2 using the structure of SQ1-KstD1 Rhodococcus erythropolis SQ1 (PDB ID 4C3Y). Enzyme KstD1 and KstD2 belongs to clusters 1 and 2, respectively -, 762659 1.3.99.4 additional information the key residues of isozyme KsdD5 with more versatility are revealed by structural modeling and site-directed mutagenesis. Enzyme residues Y528 and G532 act as an electrophile to promote labilization of the C2 hydrogen atoms of the 3-oxosteroid substrate. With the assistance of Y118, the general base Y355 captured the axial beta-hydrogen from the C2 atom as a proton, whereas FAD accepts the axial alpha-hydrogen from the C1 atom of the substrate as a hydride ion. Finally, a double bond between the C1 and C2 atoms is formed. Local models of the active site residues Y118, Y355, Y528, and G532, A255, R256, G258, G259, and L261, and F266 and R273 for KsdD5 with cofactor FAD -, 763180 1.3.99.4 additional information three-dimensional structure of a 3-oxosteroid DELTA1-dehydrogenase and structure-function analysis, enzyme reaction mechanism analysis, overview 763443 1.3.99.4 additional information three-dimensional structure of a 3-oxosteroid DELTA1-dehydrogenase and structure-function analysis, enzyme reaction mechanism analysis, overview. Molecular dynamics simulations on KSTD1 from Rhodococcus erythropolis 763443 1.3.99.4 physiological function 3-ketosteroid DELTA1-dehydrogenase (KsdD) is the key enzyme responsible for DELTA1-dehydrogenation, which is one of the most valuable reactions for steroid catabolism, roles of the putative KsdD homologues in DELTA1-dehydrogenation -, 763180 1.3.99.4 physiological function 3-ketosteroid DELTA1-dehydrogenase plays a crucial role in the early steps of steroid degradation by introducing a double bond between the C1 and C2 atoms of the A-ring of its 3-ketosteroid substrates -, 723868 1.3.99.4 physiological function 3-ketosteroid-DELTA1-dehydrogenase (KstD) catalyzes DELTA1-dehydrogenation and is involved in the steroid catabolism -, 762659 1.3.99.4 physiological function 3-oxosteroid DELTA1-dehydrogenases (DELTA1-KSTDs) are FAD-dependent enzymes that catalyze the introduction of a double bond between the C1 and C2 atoms of the A-ring of 3-ketosteroid substrates. They play a critical role in the early steps of the degradation of the steroid core. Enzyme DELTA1-KSTD is also essential for steroid ring opening under anaerobic conditions 763443 1.3.99.4 physiological function aerobic degradation of the sterol tetracyclic nucleus by microorganisms comprises the catabolism of A/B-rings, followed by that of C/D-rings. B-ring rupture at the C9,10-position is a key step involving 3-ketosteroid DELTA1-dehydrogenase (KstD) and 3-ketosteroid 9alpha-hydroxylase (KstH). Their activities lead to the aromatization of C4,5-en-containing A-ring causing the rupture of B-ring. C4,5alpha-hydrogenated 3-ketosteroid can be produced by the growing microorganism containing a 5alpha-reductase. In this case, the microorganism synthesizes, in addition to KstD and KstH, a 3-ketosteroid DELTA4-(5alpha)-dehydrogenase (Kst4D) in order to produce the A-ring aromatization, and consequently B-ring rupture. KstD and Kst4D are FAD-dependent oxidoreductases. KstH is composed of a reductase and a monooxygenase. This last component is the catalytic unit, it contains a Rieske-[2Fe-2S] center with a non-heme mononuclear iron in the active site. The characterized KstDs are active on 3-ketosteroids containing a short C17-chain or devoid of this chain. C-4,5-hydrogenated 3-ketosteroids are substrates, only if they are of the 5alpha-configuration. The DELTA1-dehydrogenation of 3-keto-4-en-steroid with KstD, purified from Nocardia corallina, is stimulated by molecular oxygen with stoichiometric production of hydrogen peroxide and 3-keto-1,4-diene-steroid. In addition, the purified KstD catalyzes hydrogen transfer from 3-keto-4-ene-steroid (donor) into 3-keto-1,4-dienesteroid (acceptor), e.g. progesterone to 1,4-androstadiene-3,17-dione (ADD). The purified KstD of N. corallina catalyzes efficiently the aromatization of A-ring of 19-nortestosterone and 19-norandrostenedione to produce respectively beta-estradiol and estrone (phenolic compounds). Also, 19-hydroxytestosterone, 19-hydroxyandrostenedione, and 19-oxotestosterone are reported to be substrates for this KstD. Their dehydrogenation produces the respective phenolic steroids. This steroid A-ring aromatization with the isolated KstD is similar to an earlier bioconversion, carried out using microbial cultures on 19-hydroxy-4-stene-3-one. The process of this bioconversion consists of the 19-hydroxystenone side chain cleavage first and second, the A-ring aromatization of the steroid derivative, producing beta-estradiol and/or estrone. Microbial 9alpha-hydroxylation does not occur in the process, due to the C19-hydroxyl group steric hindrance -, 763042 1.3.99.4 physiological function the enzyme functions in the conversion of 4-ene-3-oxosteroid to 1,4-diene-3-oxosteroid by trans-axial elimination of the Cl and C2 hydrogens, it is active in DELTA1-dehydrogenation in fusidane antibiotic biosynthesis, an important transformations in the synthesis of steroid hormones -, 724074