Affiliation:
1. Laboratory of Molecular Microbiology, Institute of Plant Physiology and Ecology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai 200032, People's Republic of China
Abstract
ABSTRACT
The gene encoding a novel penicillin G acylase (PGA), designated
pgaW
, was cloned from
Achromobacter xylosoxidans
and overexpressed in
Escherichia coli
. The
pgaW
gene contains an open reading frame of 2,586 nucleotides. The deduced protein sequence encoded by
pgaW
has about 50% amino acid identity to several well-characterized PGAs, including those of
Providencia rettgeri
,
Kluyvera cryocrescens
, and
Escherichia coli
. Biochemical studies showed that the optimal temperature for this novel PGA (PGA650) activity is greater than 60°C and its half-life of inactivation at 55°C is four times longer than that of another previously reported thermostable PGA from
Alcaligenes faecalis
(R. M. D. Verhaert, A. M. Riemens, J. V. R. Laan, J. V. Duin, and W. J. Quax, Appl. Environ. Microbiol. 63:3412-3418, 1997). To our knowledge, this is the most thermostable PGA ever characterized. To explore the molecular basis of the higher thermostability of PGA650, homology structural modeling and amino acid composition analyses were performed. The results suggested that the increased number of buried ion pair networks, lower N and Q contents, excessive arginine residues, and remarkably high content of proline residues in the structure of PGA650 could contribute to its high thermostability. The unique characteristic of higher thermostability of this novel PGA provides some advantages for its potential application in industry.
Publisher
American Society for Microbiology
Subject
Ecology,Applied Microbiology and Biotechnology,Food Science,Biotechnology
Cited by
34 articles.
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