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The biological function of the bacterial isochorismatase-like hydrolase SttH.

Authors
Type
Published Article
Journal
Bioscience Biotechnology and Biochemistry
1347-6947
Publisher
Informa UK (Taylor & Francis)
Publication Date
Volume
73
Issue
11
Pages
2494–2500
Identifiers
PMID: 19897889
Source
Medline
License
Unknown

Abstract

The streptothricin hydrolase (SttH), which is a member of the isochorismatase-like hydrolase (ILH) super-family, catalyzes the hydrolysis of the streptolidine lactam group in streptothricin (ST) antibiotics, thereby inactivating them. In this study we identified a novel homologous gene (sttH-sn) and sequenced the flanking regions of the sttH and sttH-sn genes. The organization of genes around the sttH, sttH-sn, and ILH genes revealed that a number of the genes were clustered with genes encoding oxidoreductases with molybdopterin binding subunits, suggesting that the true role of these gene products (SttHs and a number of ILHs) might have to do with the chemical modification of molybdopterin, rather than ST-resistance. In addition, mutant enzymes were constructed in which Ser was substituted for highly conserved Cys-176 and Cys-158 of SttH and SttH-sn respectively, and no enzyme activities were detected. Thus, biochemically, these ILHs were found to be "cysteine hydrolases."

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