Cardiolipin synthases in bacteria.
Item
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Title
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Cardiolipin synthases in bacteria.
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Identifier
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AAI3024796
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identifier
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3024796
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Creator
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Guo, Dagang.
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Contributor
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Adviser: Burton E. Tropp
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Date
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2001
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Language
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English
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Publisher
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City University of New York.
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Subject
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Chemistry, Biochemistry | Biology, Molecular
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Abstract
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The gene that codes for cardiolipin (CL) synthase in the alkaliphilic bacteria Bacillus firmus was cloned and sequenced. The predicted amino acid sequence of the gene product is homologous to Escherichia coli CL synthase. Both enzymes belong to a protein superfamily that also includes phospholipase D. The B. firmus CL synthase was amplified in E. coli. A membrane fraction containing the overproduced enzyme converts phosphatidylglycerol to CL and glycerol. The B. firmus CL synthase shows similar kinetic characteristics as that of its E. coli counterpart.;A B. firmus strain containing a cls null mutation was constructed. Little, if any, CL was detected in the mutant strain. The cls null mutant grows normally in rich medium at pH10.5, indicating a high concentration of CL is not essential for B. firmus to grow under alkaline conditions. The mutant strain showed some growth difficulties when malate (a non-fermentable carbon source), but not glucose (a fermentable carbon source) was used as the carbon source.;The E. coli open reading frame f413, which has the potential to code for a polypeptide homologous to CL synthase, was cloned. Its polypeptide product has a molecular mass of 48 kDa, is membrane-bound, and catalyzes CL formation but does not hydrolyze CL. A comparison of the sequences predicted for the polypeptides encoded by f413 and cls indicates that the N-terminal residues specified by cls may be unnecessary for CL synthase activity. Construction of a truncated cls gene and characterization of its polypeptide product have confirmed this conclusion.
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Type
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dissertation
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Source
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PQT Legacy CUNY.xlsx
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degree
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Ph.D.
