Interaction between the membrane protein of a pathogen and insect microfilament complex determines insect-vector specificity.
Many insect-transmissible pathogens are transmitted by specific insect species and not by others, even if they are closely related. The molecular mechanisms underlying such strict pathogen-insect specificity are poorly understood. Candidatus Phytoplasma asteris, OY strain, line W (OY), is a phytopathogenic bacterium transmitted from plant to plant by sap-feeding insect vectors (leafhoppers). Our study focused on an abundant cell-surface membrane protein of the phytoplasma named antigenic membrane protein (Amp), which is not homologous with any reported functional protein. Immunofluorescence microscopy of the phytoplasma-infected insect showed that OY phytoplasma was localized to the microfilaments of the visceral smooth muscle surrounding the insect's intestinal tract. The affinity column assay showed that Amp forms a complex with three insect proteins: actin, myosin heavy chain, and myosin light chain. Amp-microfilament complexes were detected in all OY-transmitting leafhopper species, but not in the non-OY-transmitting leafhoppers, suggesting that the formation of the Amp-microfilament complex is correlated with the phytoplasma-transmitting capability of leafhoppers. Although several studies have reported interactions between pathogens and mammalian microfilaments, this is an example of host-specific interactions between a bacterial surface protein and a host microfilament in insect cells. Our data also suggest that the utilization of a host microfilament may be a universal system for pathogenic bacteria infecting mammals or insects.
Laboratory of Plant Pathology, Department of Agricultural and Environmental Biology, Graduate School of Agricultural and Life Sciences, University of Tokyo, 1-1-1 Yayoi, Bunkyo-ku, Tokyo 113-8657, Japan.
Shiho
S
Suzuki
Kenro
K
Oshima
Shigeyuki
S
Kakizawa
Ryo
R
Arashida
Hee-Young
HY
Jung
Yasuyuki
Y
Yamaji
Hisashi
H
Nishigawa
Masashi
M
Ugaki
Shigetou
S
Namba
D008841:Actin Cytoskeleton / Q000378:metabolism / Q000382:microbiology; D000199:Actins / Q000378:metabolism; D000818:Animals; D001426:Bacterial Proteins / Q000378:metabolism*; D001483:Base Sequence; D003001:Cloning, Molecular; D018076:DNA, Complementary / Q000235:genetics; D017344:Genes, Insect; D006430:Hemiptera / Q000378:metabolism / Q000382:microbiology; D019476:Insect Proteins / Q000235:genetics / Q000378:metabolism; D007303:Insect Vectors / Q000378:metabolism / Q000382:microbiology*; D008565:Membrane Proteins / Q000378:metabolism*; D046912:Multiprotein Complexes; D009218:Myosins / Q000378:metabolism; D045582:Phytoplasma / Q000378:metabolism / Q000472:pathogenicity*; D010935:Plant Diseases / Q000382:microbiology; D013045:Species Specificity; D019032:Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization
D000199:Actins; D001426:Bacterial Proteins; D018076:DNA, Complementary; D019476:Insect Proteins; D008565:Membrane Proteins; D046912:Multiprotein Complexes; D009218:Myosins