Cloning and Nucleotide Sequencing of a Staphylococcus aureus Gene Encoding a Branched-Chain-Amino-Acid Transporter

Abstract

We recently characterized a transposon-induced NaCl-sensitive mutant of Staphylococcus aureus (U. Vijaranakul, M. J. Nadakavukaren, D. O. Bayles, B. J. Wilkinson, and R. K. Jayaswal, Appl. Environ. Microbiol. 63:1889–1897, 1997). To further characterize this mutant, we determined the nucleotide sequence at the insertion site of the transposon on the S. aureuschromosome. Nucleotide sequencing revealed a 1,326-bp open reading frame (ORF442) encoding a hydrophobic 442-amino-acid polypeptide with a calculated molecular mass of 49,058 Da. The hydrophilicity profile of the gene product revealed the existence of 12 hydrophobic domains predicted to form membrane-associated α-helices. Comparison of the amino acid sequence of ORF442 with amino acid sequences in the GenBank database showed extensive homology with the branched-chain-amino-acid transport genes of gram-positive and gram-negative bacteria. This is the first brnQ gene in staphylococci to be described.

Molecular Characterization of a Chromosomal Determinant Conferring Resistance to Zinc and Cobalt Ions in Staphylococcus aureus

“…Various known S. aureus gene clones available in our laboratory were used to explore the location of znt on the bacterial chromosome. These include lytI (15), lytM (24), atl (21), brnQ (30), and others. Dot blot studies showed hybridization of znt with the cosmid clones containing the lytI gene, thus mapping it within the SmaI-B fragment of S. aureus (14).…”

Structures of the first representatives of Pfam family PF06684 (DUF1185) reveal a novel variant of theBacilluschorismate mutase fold and suggest a role in amino-acid metabolism

“…Members of the DUF1185 family are also present in several human and animal pathogens from burkholderia and bordetella, as well as clostridia, where their genome location on virulence islands suggests a possible role in pathogenesis (Nierman et al, 2004). In some pathogenic bacteria, one of the modes of BCAA transportation is thought to be sensitive to stress induced by changes in osmolarity, pH or temperature (Vijaranakul et al, 1998). In this context, BB2672 and its homologs might present attractive drug targets since, similar to chorismate mutases, DUF1185 homologs are not found in mammals.…”

Effects of Growth at Low Water Activity on the Thermal Tolerance of Staphylococcus aureus

“…Although the rate of synthesis of most cellular proteins is decreased under these conditions, the rate of synthesis of certain cellular proteins, which may represent osmotic stress proteins or general stress proteins, increases in response to a decrease in growth medium a w (5,(11)(12)(13)(14)(15). Curiously, despite the great importance of the stress tolerance response of S. aureus, the identity of only a few potential stress proteins of S. aureus has been established (2,41,42).…”