title: Proteomic Investigation of Photorhabdus Bacteria for Nematode-Host Specificity.
abstract: Majority of animals form symbiotic relationships with bacteria. Based on the number of bacterial species associating with an animal, these symbiotic associations can be mono-specific, relatively simple (2-25 bacterial species/animal) or highly complex (>10(2)-10(3) bacterial species/animal). Photorhabdus (family-Enterobacteriaceae) forms a mono-specific symbiotic relationship with the entomopathogenic nematode Heterorhabditis. This system provides a tractable genetic model for animal-microbe symbiosis studies. Here, we investigated the bacterial factors that may be responsible for governing host specificity between nematode and their symbiont bacteria using proteomics approach. Total protein profiles of P. luminescens ssp. laumondii (host nematode- H. bacteriophora) and P. luminescens ssp. akhurstii (host nematode- H. indica) were compared using 2-D gel electrophoresis, followed by identification of differentially expressed proteins by MALDI-TOF MS. Thirty-nine unique protein spots were identified - 24 from P. luminescens ssp. laumondii and 15 from P. luminescens ssp. akhurstii. These included proteins that might be involved in determining host specificity directly (for e.g. pilin FimA, outer membrane protein A), indirectly through effect on bacterial secondary metabolism (for e.g. malate dehydrogenase Mdh, Pyruvate formate-lyase PflA, flavo protein WrbA), or in a yet unknown manner (for e.g. hypothetical proteins, transcription regulators). Further functional validation is needed to establish the role of these bacterial proteins in nematode-host specificity.
authors.affiliation: Division of Nematology, ICAR- Indian Agricultural Research Institute, Pusa Campus, New Delhi, 110012 India.|ICAR-National Research Center on Plant Biotechnology, Pusa Campus, New Delhi, 110012 India.
authors.forename: Ram
authors.initials: R
authors.lastname: Kumar
authors.affiliation: Division of Nematology, ICAR- Indian Agricultural Research Institute, Pusa Campus, New Delhi, 110012 India.
authors.forename: Jyoti
authors.initials: J
authors.lastname: Kushwah
authors.affiliation: Division of Nematology, ICAR- Indian Agricultural Research Institute, Pusa Campus, New Delhi, 110012 India.
authors.forename: Sudershan
authors.initials: S
authors.lastname: Ganguly
authors.affiliation: Department of Biotechnology and Biosciences, Banasthali Vidyapeeth, Jaipur, Rajasthan India.
authors.forename: Veena
authors.initials: V
authors.lastname: Garg
authors.affiliation: Division of Nematology, ICAR- Indian Agricultural Research Institute, Pusa Campus, New Delhi, 110012 India.
authors.forename: Vishal S
authors.initials: VS
authors.lastname: Somvanshi
keywords: 2-D gel electrophoresis; Heterorhabditis; Host specificity; Photorhabdus; Proteomics; Symbiosis