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Peptide permeases modulate transformation in Streptococcus pneumoniae
Author(s) -
Pearce B. J.,
Naughton A. M.,
Masure H. R.
Publication year - 1994
Publication title -
molecular microbiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.857
H-Index - 247
eISSN - 1365-2958
pISSN - 0950-382X
DOI - 10.1111/j.1365-2958.1994.tb01076.x
Subject(s) - permease , biology , mutant , transformation (genetics) , peptide sequence , biochemistry , bacillus subtilis , membrane transport protein , gene , lactose permease , genetics , bacteria , transporter
Summary 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 consistentiy transformed 10‐foid 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 SpooKA which is a regulatory element in the process of transformation and sporulation in Bacillus subtilis. PIpA fusions to alkaline phosphatase (PhoA) were shown to be membrane associated and labelled with [ 3 H]‐palmitic acid, which probably serves as a membrane anchor. Experiments designed to define the roles of the pIpA 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 (ill) 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.