Identification of cold-inducible inner membrane proteins of the psychrotrophic bacterium, Shewanella livingstonensis Ac10, by proteomic analysis.
Shewanella livingstonensis Ac10 is a psychrotrophic Gram-negative bacterium that grows at temperatures close to 0°C. Previous proteomic studies of this bacterium identified cold-inducible soluble proteins and outer membrane proteins that could possibly be involved in its cold adaptation (Kawamoto et al. in Extremophiles 11:819-826, 2007). In this study, we established a method for separating the inner and outer membranes by sucrose density gradient ultracentrifugation and performed proteomic studies of the inner membrane fraction. The cells were grown at temperatures of 4 and 18°C, and phospholipid-enriched inner membrane fractions were obtained. Two-dimensional polyacrylamide gel electrophoresis and peptide mass fingerprinting analysis of the proteins identified 14 cold-inducible proteins (more than a 2-fold increase at 4°C). Six of these proteins were predicted to be inner membrane proteins. Two predicted periplasmic proteins, 5 predicted cytoplasmic proteins, and 1 predicted outer membrane protein were also found in the inner membrane fraction, suggesting their association with the inner membrane proteins and/or lipids. These cold-inducible proteins included proteins that are presumed to be involved in chemotaxis (AtoS and PspA), membrane protein biogenesis (DegP, SurA, and FtsY), and morphogenesis (MreB). These findings provide a basis for further studies on the cold-adaptation mechanism of this bacterium.
Institute for Chemical Research, Kyoto University, Uji, Kyoto, 611-0011, Japan.
Jungha
J
Park
Jun
J
Kawamoto
Nobuyoshi
N
Esaki
Tatsuo
T
Kurihara
D000222:Adaptation, Physiological / Q000235:genetics; D001419:Bacteria / Q000235:genetics; D001425:Bacterial Outer Membrane Proteins / Q000378:metabolism; D001426:Bacterial Proteins / Q000737:chemistry; D002499:Centrifugation, Density Gradient / Q000379:methods; D003080:Cold Temperature; D003593:Cytoplasm / Q000378:metabolism; D015180:Electrophoresis, Gel, Two-Dimensional / Q000379:methods; D015964:Gene Expression Regulation, Bacterial; D006090:Gram-Negative Bacteria / Q000378:metabolism; D008055:Lipids / Q000737:chemistry; D040901:Proteomics / Q000379:methods*; D020592:Shewanella / Q000378:metabolism*; D013696:Temperature
D001425:Bacterial Outer Membrane Proteins; D001426:Bacterial Proteins; D008055:Lipids