Cloning of immunodominant membrane protein genes of phytoplasmas and their in planta expression.
Phytoplasmas are plant pathogenic bacteria that cause devastating yield losses in diverse crops worldwide. Although the understanding of the pathogen biology is important in agriculture, the inability to culture phytoplasmas has hindered their full characterization. Previous studies demonstrated that immunodominant membrane proteins could be classified into three types, immunodominant membrane protein (Imp), immunodominant membrane protein A (IdpA), and antigenic membrane protein (Amp), and they are nonhomologous to each other. Here, cloning and sequencing of imp-containing genomic fragments were performed for several groups of phytoplasma including the aster yellows and rice yellow dwarf groups, for which an imp sequence has not previously been reported. Sequence comparison analysis revealed that Imps are highly variable among phytoplasmas, and clear positive selection was observed in several Imps, suggesting that Imp has important roles in host-phytoplasma interactions. As onion yellows (OY) phytoplasma was known to have Amp as the immunodominant membrane protein, the protein accumulation level of Imp in planta was measured compared with that of Amp. The resulting accumulation of Imp was calculated as approximately one-tenth that of Amp, being consistent with the immunodominant property of Amp in OY. It is suggested that an ancestral type of immunodominant membrane protein could be Imp, and subsequently the expression level of Amp or IdpA is increased in several phytoplasma groups.
Kakizawa
Shigeyuki
S
Laboratory of Plant Pathology, Division of Agricultural and Life Sciences, Graduate School of Agricultural and Life Sciences, The University of Tokyo, Tokyo, Japan.
Oshima
Kenro
K
Ishii
Yoshiko
Y
Hoshi
Ayaka
A
Maejima
Kensaku
K
Jung
Hee-Young
HY
Yamaji
Yasuyuki
Y
Namba
Shigetou
S
D001426:Bacterial Proteins / Q000235:genetics / Q000276:immunology / Q000378:metabolism; D003001:Cloning, Molecular; D019143:Evolution, Molecular; D016056:Immunodominant Epitopes / Q000235:genetics / Q000276:immunology / Q000378:metabolism; D008565:Membrane Proteins / Q000235:genetics* / Q000276:immunology / Q000378:metabolism; D010802:Phylogeny; D045582:Phytoplasma / Q000235:genetics / Q000276:immunology / Q000378:metabolism*; D010935:Plant Diseases / Q000382:microbiology; D010944:Plants / Q000378:metabolism / Q000382:microbiology*; D012641:Selection, Genetic; D017422:Sequence Analysis, DNA
D001426:Bacterial Proteins; D016056:Immunodominant Epitopes; D008565:Membrane Proteins