Genetic Analysis of a pH-Regulated Operon from Rhizobium tropici CIAT899 Involved in Acid Tolerance and Nodulation Competitiveness
- 1 February 2003
- journal article
- Published by Scientific Societies in Molecular Plant-Microbe Interactions®
- Vol. 16 (2), 159-168
- https://doi.org/10.1094/mpmi.2003.16.2.159
Abstract
Rhizobium tropici CIAT899 is highly acid tolerant and a good competitor for Phaseolus vulgaris nodule occupancy at low pH values. Using Tn5 mutagenesis, we identified an operon required for acid tolerance and nodulation competitiveness. The insertion was mapped to the 5' end of atvA, encoding a product with high sequence identity to the agro-bacterial AcvB virulence protein. Complementation analyses indicated that atvA is an ortholog of acvB, both genes being required for acid tolerance. A Ser/Ala substitution in the LIPASE_SER motif of AtvA resulted in an acid sensitive Fix+ but very poorly competing strain, demonstrating that Ser-313 is essential for AtvA function. atvA is the second gene in an operon that is transcriptionally upregulated by acid shock. The acid-responsive promoter was mapped to a 469-bp intergenic region located upstream of lpiA, the first gene in the operon. lpiA-like genes are found in several alpha, beta, and gamma Proteobacteria that interact with eukaryotic host cells, and they are predicted to encode membrane proteins related to the FmtC/MprF family from low G+C Firmicutes. The latter proteins are involved in resistance to cationic antimicrobial peptides. A nonpolar deletion in lpiA caused a sevenfold decrease in relative nodulation competitiveness.This publication has 64 references indexed in Scilit:
- Antimicrobial peptides of multicellular organismsNature, 2002
- The Genome of the Natural Genetic Engineer Agrobacterium tumefaciens C58Science, 2001
- Intracellular accommodation of microbes by plants: a common developmental program for symbiosis and disease?Current Opinion in Plant Biology, 2000
- Plant defense peptidesPeptide Science, 1998
- Four new derivatives of the broad-host-range cloning vector pBBR1MCS, carrying different antibiotic-resistance cassettesGene, 1995
- An Agrobacterium virulence factor encoded by a Ti plasmid gene or a chromosomal gene is required for T‐DNA transfer into plantsMolecular Microbiology, 1995
- Small mobilizable multi-purpose cloning vectors derived from the Escherichia coli plasmids pK18 and pK19: selection of defined deletions in the chromosome of Corynebacterium glutamicumGene, 1994
- Acid pH tolerance in strains of Rhizobium and Bradyrhizobium, and initial studies on the basis for acid tolerance of Rhizobium tropici UMR1899Canadian Journal of Microbiology, 1994
- Bacteroids in theRhizobium-Legume Symbiosis Inhabit a Plant Internal Lytic Compartment: Implications for other Microbial EndosymbiosesJournal of Experimental Botany, 1989
- A Broad Host Range Mobilization System for In Vivo Genetic Engineering: Transposon Mutagenesis in Gram Negative BacteriaBio/Technology, 1983