scouring around, getting ready for ICAAC, and ran across this....
J Bacteriol 1999 Jun;181(12):3666-73
Role in cell permeability of an essential two-component system in
Staphylococcus aureus.
Martin PK, Li T, Sun D, Biek DP, Schmid MB
Microcide Pharmaceuticals, Inc., Mountain View, California 94043, USA. martin@microcide.com
A temperature-sensitive lethal mutant of Staphylococcus aureus was found to harbor a mutation in the uncharacterized
two-component histidine kinase (HK)-response regulator (RR) pair encoded by yycFG; orthologues of yycFG could be
identified in the genomes of Bacillus subtilis and other gram-positive bacteria. Sequence analysis of the mutant revealed a point
mutation resulting in a nonconservative change (Glu to Lys) in the regulator domain of the RR at position 63. To confirm that
this signal transduction system was essential, a disrupted copy of either the RR (yycF) or the HK (yycG) was constructed with
a set of suicide vectors and used to generate tandem duplications in the chromosome. Resolution of the duplications, leaving an
insertion in either the yycF or the yycG coding region, was achieved only in the presence of an additional wild-type copy of the
two open reading frames. Phenotypic characterization of the conditional lethal mutant showed that at permissive growth
conditions, the mutant was hypersusceptible to macrolide and lincosamide antibiotics, even in the presence of the ermB
resistance determinant. Other mutant phenotypes, including hypersensitivity to unsaturated long-chain fatty acids and
suppression of the conditional lethal phenotype by high sucrose and NaCl concentrations, suggest that the role of the
two-component system includes the proper regulation of bacterial cell wall or membrane composition. The effects of this point
mutation are strongly bactericidal at the nonpermissive temperature, indicating that this pathway provides an excellent target for
the identification of novel antibiotics. |
