• Open Access

The ABC transporters in Candidatus Liberibacter asiaticus

Authors

  • Wenlin Li,

    1. Department of Biochemistry and Department of Biophysics, University of Texas Southwestern Medical Center, Dallas, Texas 75390-9050
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  • Qian Cong,

    1. Department of Biochemistry and Department of Biophysics, University of Texas Southwestern Medical Center, Dallas, Texas 75390-9050
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  • Jimin Pei,

    1. Howard Hughes Medical Institute, University of Texas Southwestern Medical Center, Dallas, Texas 75390-9050
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  • Lisa N. Kinch,

    1. Howard Hughes Medical Institute, University of Texas Southwestern Medical Center, Dallas, Texas 75390-9050
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  • Nick V. Grishin

    Corresponding author
    1. Department of Biochemistry and Department of Biophysics, University of Texas Southwestern Medical Center, Dallas, Texas 75390-9050
    2. Howard Hughes Medical Institute, University of Texas Southwestern Medical Center, Dallas, Texas 75390-9050
    • Howard Hughes Medical Institute, University of Texas Southwestern Medical Center, 5323 Harry Hines Blvd, Dallas, TX 75390-9050
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Abstract

Candidatus Liberibacter asiaticus (Ca. L. asiaticus) is a Gram-negative bacterium and the pathogen of Citrus Greening disease (Huanglongbing, HLB). As a parasitic bacterium, Ca. L. asiaticus harbors ABC transporters that play important roles in exchanging chemical compounds between Ca. L. asiaticus and its host. Here, we analyzed all the ABC transporter-related proteins in Ca. L. asiaticus. We identified 14 ABC transporter systems and predicted their structures and substrate specificities. In-depth sequence and structure analysis including multiple sequence alignment, phylogenetic tree reconstruction, and structure comparison further support their function predictions. Our study shows that this bacterium could use these ABC transporters to import metabolites (amino acids and phosphates) and enzyme cofactors (choline, thiamine, iron, manganese, and zinc), resist to organic solvent, heavy metal, and lipid-like drugs, maintain the composition of the outer membrane (OM), and secrete virulence factors. Although the features of most ABC systems could be deduced from the abundant experimental data on their orthologs, we reported several novel observations within ABC system proteins. Moreover, we identified seven nontransport ABC systems that are likely involved in virulence gene expression regulation, transposon excision regulation, and DNA repair. Our analysis reveals several candidates for further studies to understand and control the disease, including the type I virulence factor secretion system and its substrate that are likely related to Ca. L. asiaticus pathogenicity and the ABC transporter systems responsible for bacterial OM biosynthesis that are good drug targets. Proteins 2012. © 2012 Wiley Periodicals, Inc.

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