Affiliation:
1. Department of Molecular and Cell Biology, University of Connecticut, 91 North Eagleville Rd., Unit 3125, Storrs, Connecticut 06269
Abstract
ABSTRACT
Frankia
species are the most geographically widespread gram-positive plant symbionts, carrying out N
2
fixation in root nodules of trees and woody shrubs called actinorhizal plants. Taking advantage of the sequencing of three
Frankia
genomes, proteomics techniques were used to investigate the population of extracellular proteins (the exoproteome) from
Frankia
, some of which potentially mediate host-microbe interactions. Initial two-dimensional sodium dodecyl sulfate-polyacrylamide gel electrophoresis analysis of culture supernatants indicated that cytoplasmic proteins appeared in supernatants as cells aged, likely because older hyphae lyse in this slow-growing filamentous actinomycete. Using liquid chromatography coupled to tandem mass spectrometry to identify peptides, 38 proteins were identified in the culture supernatant of
Frankia
sp. strain CcI3, but only three had predicted export signal peptides. In symbiotic cells, 42 signal peptide-containing proteins were detected from strain CcI3 in
Casuarina cunninghamiana
and
Casuarina glauca
root nodules, while 73 and 53 putative secreted proteins containing signal peptides were identified from
Frankia
strains in field-collected root nodules of
Alnus incana
and
Elaeagnus angustifolia
, respectively. Solute-binding proteins were the most commonly identified secreted proteins in symbiosis, particularly those predicted to bind branched-chain amino acids and peptides. These direct proteomics results complement a previous bioinformatics study that predicted few secreted hydrolytic enzymes in the
Frankia
proteome and provide direct evidence that the symbiosis succeeds partly, if not largely, because of a benign relationship.
Publisher
American Society for Microbiology
Subject
Ecology,Applied Microbiology and Biotechnology,Food Science,Biotechnology
Reference39 articles.
1. Alloisio, N., S. Felix, J. Marechal, P. Pujic, Z. Rouy, D. Vallenet, C. Medigue, and P. Normand. 2007. Frankia alni proteome under nitrogen-fixing and nitrogen-replete conditions. Physiol. Plant.130:450-453.
2. Bagnarol, E., J. Popovici, N. Alloisio, J. Marechal, P. Pujic, P. Normand, and M. P. Fernandez. 2007. Differential Frankia protein patterns induced by phenolic extracts from Myricaceae seeds. Physiol. Plant.130:380-390.
3. Improved Prediction of Signal Peptides: SignalP 3.0
4. Benson, D. R., and N. A. Schultz. 1990. Physiology and biochemistry of Frankia in culture, p. 107-127. In C. R. Schwintzer and J. D. Tjepkema (ed.), The biology of Frankia and actinorhizal plants. Academic Press, Inc., New York, NY.
5. Biology of Frankia strains, actinomycete symbionts of actinorhizal plants
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