Publication: Identification of motifs of Burkholderia pseudomallei BimA required for intracellular motility, actin binding, and actin polymerization
4
Issued Date
2011-04-01
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ISSN
10985530
00219193
00219193
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2-s2.0-79955460957
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Mahidol University
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SCOPUS
Bibliographic Citation
Journal of Bacteriology. Vol.193, No.8 (2011), 1901-1910
Suggested Citation
Chayada Sitthidet, Sunee Korbsrisate, Abigail N. Layton, Terence R. Field, Mark P. Stevens, Joanne M. Stevens Identification of motifs of Burkholderia pseudomallei BimA required for intracellular motility, actin binding, and actin polymerization. Journal of Bacteriology. Vol.193, No.8 (2011), 1901-1910. doi:10.1128/JB.01455-10 Retrieved from: https://repository.li.mahidol.ac.th/handle/123456789/11573
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Title
Identification of motifs of Burkholderia pseudomallei BimA required for intracellular motility, actin binding, and actin polymerization
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Abstract
Actin-based motility of the melioidosis pathogen Burkholderia pseudomallei requires BimA (Burkholderia intracellular motility A). The mechanism by which BimA mediates actin assembly at the bacterial pole is ill-defined. Toward an understanding of the regions of B. pseudomallei BimA required for intracellular motility and the binding and polymerization of actin, we constructed plasmid-borne bimA variants and glutathione-Stransferase fusion proteins with in-frame deletions of specific motifs. A 13-amino-acid direct repeat and IP 7 proline-rich motif were dispensable for actin binding and assembly in vitro, and expression of the mutated proteins in a B. pseudomallei bimA mutant restored actin-based motility in J774.2 murine macrophage-like cells. However, two WASP homology 2 (WH2) domains were found to be required for actin binding, actin assembly, and plaque formation. A tract of five PDASX direct repeats influenced the polymerization of pyrene-actin monomers in vitro and was required for actin-based motility and intercellular spread, but not actin binding. None of the mutations impaired surface expression or polar targeting of BimA. The number of PDASX repeats varied in natural isolates from two to seven. Such repeats acted additively to promote pyrene-actin polymerization in vitro, with stepwise increases in the rate of polymerization as the number of repeats was increased. No differences in the efficiency of actin tail formation could be discerned between strains expressing BimA variants with two, five, or seven PDASX repeats. The data provide valuable new insights into the role of conserved and variable motifs of BimA in actin-based motility and intercellular spread of B. pseudomallei. © 2011, American Society for Microbiology.