Peptide permeases modulate transformation in Streptococcus pneumoniae.
To identify elements participating in the process of transformation, a bank of genetically altered mutants of Streptococcus pneumoniae with defects in exported proteins was assessed for a decrease in transformation efficiency. One mutant consistently transformed 10-fold less than the parent strain. Sequence analysis and reconstitution of the altered locus revealed a gene, plpA (permease-like protein), which encodes a putative substrate-binding protein belonging to the family of bacterial permeases responsible for peptide transport. The derived amino acid sequence for this gene was 80% similar to AmiA, a peptide-binding protein homologue from pneumococcus, and 50% similar over 230 amino acids to Spo0KA which is a regulatory element in the process of transformation and sporulation in Bacillus subtilis. PlpA fusions to alkaline phosphatase (PhoA) were shown to be membrane associated and labelled with [3H]-palmitic acid, which probably serves as a membrane anchor. Experiments designed to define the roles of the plpA and ami determinants in the process of transformation showed that: (i) mutants with defects in plpA were > 90% transformation deficient while ami mutants exhibited up to a fourfold increase in transformation efficiency; (ii) compared to the parental strain, the onset of competence in an ami mutant occurred earlier in logarithmic growth, whereas the onset was delayed in a plpA mutant; and (iii) the plpA mutation decreases the expression of a competence-regulated locus. Since the permease mutants would fail to bind specific ligands, it seems likely that the substrate-permease interaction modulates the process of transformation.
Pearce
B J
BJ
Laboratory of Molecular Infectious Diseases, Rockefeller University, New York, New York 10021.
Naughton
A M
AM
Masure
H R
HR
D000595:Amino Acid Sequence; D001426:Bacterial Proteins; D001483:Base Sequence; D002352:Carrier Proteins / Q000737:chemistry / Q000235:genetics* / Q000502:physiology; D002462:Cell Membrane / Q000378:metabolism; D005798:Genes, Bacterial / Q000235:genetics; D008074:Lipoproteins / Q000235:genetics; D026901:Membrane Transport Proteins / Q000737:chemistry / Q000235:genetics* / Q000502:physiology; D008969:Molecular Sequence Data; D009154:Mutation / Q000502:physiology; D012329:RNA, Bacterial / Q000096:biosynthesis; D012333:RNA, Messenger / Q000096:biosynthesis; D016415:Sequence Alignment; D017422:Sequence Analysis, DNA; D017386:Sequence Homology, Amino Acid; D013296:Streptococcus pneumoniae / Q000201:enzymology / Q000235:genetics*; D014169:Transformation, Bacterial
D001426:Bacterial Proteins; D002352:Carrier Proteins; D008074:Lipoproteins; D026901:Membrane Transport Proteins; C089759:PlpA protein, Streptococcus pneumoniae; D012329:RNA, Bacterial; D012333:RNA, Messenger