Bacillus subtilis amino acid content

Thermolysin belongs to a class of proteases (called neutral proteases) which are distinct from the serine proteases, sulfhydryl proteases, metal-loexopeptidases, and acid proteases. Neutral proteases A and B from Bacillus subtilis resemble thermolysin in molecular weight, substrate specificity, amino acid content, and metal ion dependence. Since physiological substrates are most likely proteins, it is difficult to design simple experiments that can be interpreted in terms of substrate specificity and relative velocities. Therefore, studies of substrate specificity and other kinetic parameters must be carried out on di- and tripeptides so that details of the mechanism of catalysis can be obtained and interpreted simply. 

In the Gram-positive bacterium Bacillus subtilis (DNA with low G + C content), three Fur-like proteins have been characterized (Bsat et al., 1998). One, called Fur, regulates mainly iron uptake and siderophore biosynthesis. A second one, called PerR, regulates peroxide stress response genes and acts with manganese as corepressor. A third one, Zur, regulates genes for zinc uptake. The Zur protein found in E. coli shows only 25 % identity to the B. subtilis Zur, while the two Fur proteins have 32 % identical amino acids. 

In chimeric isopropylmalate dehydrogenase from an extreme thermophile, Thermus thermophile, and a mesophile. Bacillus subtilis, the stability of each chimeric enzyme was also proportional to the content of the amino acid sequence from the T. thermophile enzyme (26). The thermal stability of the chimeras was also intermediate between that of the highly labile Type II hexokinase and the relatively stable Type I isozyme (57). 

Subtilisin (EC 3.4.21.4) an extracellular, single chain, alkaline serine protease from Bacillus subtilis and related species. S. are known from four different species of Bacillus S. Carlsberg (274 amino acid residues, M, 27,277), S. BPN (275 amino acid residues, M, 27,537), S. Novo (identical with S.BPN ) and S. amylosacchariticus (275 amino acid residues, M, 27671). The observed sequence differences between different S. represent conservative substitutions and are limited to the surface amino acids. Like the pancreatic proteinases, S. has catalytic Ser22i, His64 and Asnjj residues, but it is structurally very different from the other serine proteases, e. g. the active center of S. is -Thr-Ser-Met-, whereas that of the pancreatic enzymes is -Asp-Ser-Gly- pancreatic enzymes contain 4- disulfide bridges, whereas S. contains none S. contains 31 % a-helical structure and 3 spatially separated domains, whereas the pancreatic enzymes have 10-20% a-helical structure and a high content of p-structures in both types, the active center is a substrate cleft. S. also have a broader substrate specificity than the pancreatic enzymes. This is a notable example of the convergent evolution of catalytic activity in two structurally completely different classes of proteins. S. is used in the structural elucidation... 

An incompletely characterized peptidolipid with the same amino acid composition as surfactin has been isolated from the Marburg strain of Bacillus subtilis, and appeared to be located in the cell membrane. It was synthesized continuously during the growth of the bacteria and its content increased in phosphate-limited cultures (100). 

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