Essential residues in the chromate transporter ChrA of Pseudomonas aeruginosa

The chrA gene of Pseudomonas aeruginosa plasmid pUM505 encodes the hydrophobic protein ChrA, which confers resistance to chromate by the energy-dependent efflux of chromate ions. Chromate-sensitive mutants were isolated by in vivo random mutagenesis. Transport experiments with cell suspensions of se...

Full description

Saved in:
Bibliographic Details
Published inFEMS microbiology letters Vol. 232; no. 1; pp. 107 - 112
Main Authors Aguilera, Selene, Aguilar, MaEsther, Chávez, Martha P, López-Meza, Joel E, Pedraza-Reyes, Mario, Campos-García, Jesús, Cervantes, Carlos
Format Journal Article
LanguageEnglish
Published Oxford Oxford University Press 01.03.2004
Subjects
Amino acids
Cell suspensions
ChrA protein
Chromate
Chromates
Deoxyribonucleic acid
DNA
Efflux
Extrusion
Homology
Hydrophobicity
Microbiology
Mutation
Nucleotide sequence
Proteins
Pseudomonas aeruginosa
Random mutagenesis
Residues
Topology
Online AccessGet full text

Cover

More Information
Summary:The chrA gene of Pseudomonas aeruginosa plasmid pUM505 encodes the hydrophobic protein ChrA, which confers resistance to chromate by the energy-dependent efflux of chromate ions. Chromate-sensitive mutants were isolated by in vivo random mutagenesis. Transport experiments with cell suspensions of selected mutants showed that 51CrO42− extrusion was drastically lowered as compared to suspensions of the strain with the wild-type plasmid, confirming that the mutations affected a chromate efflux system. DNA sequence analysis showed that most point mutations affected amino acids clustered in the N-terminal half of ChrA, altering either cytoplasmic regions or transmembrane segments, and replaced residues moderately to highly conserved in ChrA homologs. PhoA and LacZ translational fusions were used to confirm the membrane topology at the N-terminal half of the ChrA protein.
ISSN:0378-1097
1574-6968
DOI:10.1016/S0378-10970400068-0