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" ‘Candidatus Liberibacter asiaticus’ Encodes Two Novel Autotransporters that Target to Mitochondria "
Hao, Guixia; Boyle, Michael; Zhou, Lijuan; Duan, Yongping
| Document Type
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AL
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| Record Number
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942401
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| Doc. No
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LA79c2350x
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| Language of Document
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English
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| Main Entry
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Hao, Guixia; Boyle, Michael; Zhou, Lijuan; Duan, Yongping
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| Title & Author
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‘Candidatus Liberibacter asiaticus’ Encodes Two Novel Autotransporters that Target to Mitochondria [Article]\ Hao, Guixia; Boyle, Michael; Zhou, Lijuan; Duan, Yongping
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| Title of Periodical
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Journal of Citrus Pathology
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| Volume/ Issue Number
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1
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| Date
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2014
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| Abstract
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As a phloem-limited, intracellular bacterial pathogen, ‘Candidatus Liberibacter asiaticus’ (Las) has a significantly reduced genome and causes huanglongbing (HLB), a devastating disease of citrus worldwide. In this study, we characterized two novel autotransporter proteins of Las, and redesignated them as LasA<sub>I</sub> and LasA<sub>II</sub> in lieu of the previous names Hyv<sub>I</sub> and Hyv<sub>II. </sub>Proteins secreted by the type V secretion system (T5SS), known as autotransporters, are large extracellular virulence proteins localized to the bacterial poles. Bioinformatic analyses revealed that LasA<sub>I</sub> and LasA<sub>II</sub> share the structural features of an autotransporter family containing large repeats of a passenger domain and a unique C-terminal translocator domain. When fused to the GFP gene and expressed in E. coli, the LasA<sub>I</sub> C-terminus and the full length LasA<sub>II</sub> were localized to the bacterial poles, similar to other members of autotransporter family. Despite the absence of the signal peptide, LasA<sub>I</sub> was found to localize at the cell surface by immuno-dot blot using a monoclonal antibody against the partial LasA<sub>I </sub>protein. Its surface localization was also confirmed by the removal of the LasA<sub>I </sub>antigen using a proteinase K treatment of the intact bacterial cells. When co-inoculated with a P19 gene silencing suppressor and transiently expressed in tobacco leaves, the GFP-LasA<sub>I</sub> translocator targeted to the mitochondria. This is the first report that Las encodes novel autotransporters that target to mitochondria. These findings may lead to a better understanding of the pathogenesis of this intracellular “energy parasitic” bacterium, and to more efficient characterizing new molecular targets for HLB control.
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