title: A yeast two-hybrid screen reveals a strong interaction between the Legionella chaperonin Hsp60 and the host cell small heat shock protein Hsp10.
abstract: L. pneumophila is an intracellular bacterium that replicates inside a membrane-bound vacuole called Legionella-containing vacuole (LCV), where it plentifully liberates its HtpB chaperonin. From LCV, HtpB reaches the host cell cytoplasm, where it interacts with SAMDC, a cytoplasmic protein required for synthesis of host polyamines that are important for intracellular growth of L. pneumophila. Additionally, cytoplasmic expression of HtpB in S. cerevisiae induces pseudohyphal growth, and in mammalian cells recruits mitochondria to LCV, and modifies actin microfilaments organization. This led us to hypothesize here that HtpB recruits a protein(s) from eukaryotic cells that is involved in the emergence of the aforementioned phenotypes. To identify this protein, a commercially available HeLa cDNA library was screened using a yeast two-hybrid system. Approximately 5×10(6) yeast clones carrying HeLa cDNA library plasmid were screened. Twenty-one positive clones were identified. DNA sequence analysis revealed that all of these positive clones encoded the mammalian small heat shock protein Hsp10. Based on the fact that chaperonions are required to interact with co-chaperonins to function properly in protein folding, we believe that HtpB recruits the host cell Hsp10 to appropriately interact with SAMDC and to induce the multifunction phenotypes deemed important in L. pneumophila pathogenesis.
authors.affiliation: Department of Health Sciences, Biomedical Sciences Program, College of Arts and Sciences and Biomedical Research Center, Qatar University , Doha, State of Qatar.
authors.forename: Gheyath K
authors.initials: GK
authors.lastname: Nasrallah
mesh_terms: D018835:Chaperonin 10 / Q000235:genetics / Q000378:metabolism*; D018834:Chaperonin 60 / Q000235:genetics / Q000378:metabolism*; D015723:Gene Library; D006367:HeLa Cells; D050888:Heat-Shock Proteins, Small / Q000235:genetics / Q000378:metabolism*; D006801:Humans; D016952:Legionella pneumophila / Q000235:genetics / Q000378:metabolism*; D008954:Models, Biological; D010641:Phenotype; D011993:Recombinant Fusion Proteins; D012441:Saccharomyces cerevisiae / Q000235:genetics / Q000378:metabolism; D020798:Two-Hybrid System Techniques
chemical_list: D018835:Chaperonin 10; D018834:Chaperonin 60; D050888:Heat-Shock Proteins, Small; D011993:Recombinant Fusion Proteins
keywords: HtpB; L. pneumophila; chaperonin; co-chaperonin Hsp10