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 modifi es actin
microfi laments 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 5×106 yeast
clones carrying HeLa cDNA library plasmid were screened. Twenty-one positive
clones were identifi ed. 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.
DOI/handle
http://dx.doi.org/10.1556/030.62.2015.2.3http://dx.doi.org/10.1556/030.62.2015.2.3
http://hdl.handle.net/10576/4754
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