Identification and evolutionary analysis of putative cytoplasmic mcpa-like protein in a bacterial strain living in siymbiosis with a mycorrhizal fungus

In this paper we report the identification and characterization of a DNA region containing putative mcpA-like gene coding for a Methyl accepting chemotaxis protein (Mcp) and belonging to a bacterial strain, endosymbiont of the arbuscular mycorrhizal fungus Gigaspora margarita and identified as a Burkholderia on the basis of the 16 S rDNA sequence. A genomic library of total DNA extracted from the fungal spores was also representative of the bacterial genome and was used to investigate the prokaryotic genome. PCR experiments with primers designed on the Burkholderia mcpA-like gene and Southern blot analysis demonstrate that they actually belong to the genome of G. margarita endosymbiont. Reverse transcriptase PCR experiments with the same primers described above and performed on total RNA extracted from the fungal spores demonstrate the gene expression. In addition a detailed comparative analysis of the bacterial Mcps available in databases allowed us to draw a possible evolutionary pathway leading to the present-day mcpA genes.