Linked Life Data

17280684

Source:http://linkedlifedata.com/resource/pubmed/id/17280684

Statements in which the resource exists as a subject.
PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
3
pubmed:dateCreated
2007-3-6
pubmed:abstractText
All secreted proteins in Escherichia coli must be maintained in an export-competent state before translocation across the inner membrane. In the case of the Sec pathway, this function is carried out by the dedicated SecB chaperone and the general chaperones DnaK-DnaJ-GrpE and GroEL-GroES, whose job collectively is to render substrate proteins partially or entirely unfolded before engagement of the translocon. To determine whether these or other general molecular chaperones are similarly involved in the translocation of folded proteins through the twin-arginine translocation (Tat) system, we screened a collection of E. coli mutant strains for their ability to transport a green fluorescent protein (GFP) reporter through the Tat pathway. We found that the molecular chaperone DnaK was essential for cytoplasmic stability of GFP bearing an N-terminal Tat signal peptide, as well as for numerous other recombinantly expressed endogenous and heterologous Tat substrates. Interestingly, the stability conferred by DnaK did not require a fully functional Tat signal as substrates bearing translocation defective twin lysine substitutions in the consensus Tat motif were equally unstable in the absence of DnaK. These findings were corroborated by crosslinking experiments that revealed an in vivo association between DnaK and a truncated version of the Tat substrate trimethylamine N-oxide reductase (TorA502) bearing an RR or a KK signal peptide. Since TorA502 lacks nine molybdo-cofactor ligands essential for cofactor attachment, the involvement of DnaK is apparently independent of cofactor acquisition. Finally, we show that the stabilizing effects of DnaK can be exploited to increase the expression and translocation of Tat substrates under conditions where the substrate production level exceeds the capacity of the Tat translocase. This latter observation is expected to have important consequences for the use of the Tat system in biotechnology applications where high levels of periplasmic expression are desirable.
pubmed:grant
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
IM
pubmed:chemical
http://linkedlifedata.com/resource/pubmed/chemical/Carrier Proteins, http://linkedlifedata.com/resource/pubmed/chemical/Chaperonin 10, http://linkedlifedata.com/resource/pubmed/chemical/Chaperonin 60, http://linkedlifedata.com/resource/pubmed/chemical/DnaJ protein, E coli, http://linkedlifedata.com/resource/pubmed/chemical/Escherichia coli Proteins, http://linkedlifedata.com/resource/pubmed/chemical/Green Fluorescent Proteins, http://linkedlifedata.com/resource/pubmed/chemical/HSP40 Heat-Shock Proteins, http://linkedlifedata.com/resource/pubmed/chemical/HSP70 Heat-Shock Proteins, http://linkedlifedata.com/resource/pubmed/chemical/Maltose-Binding Proteins, http://linkedlifedata.com/resource/pubmed/chemical/Membrane Transport Proteins, http://linkedlifedata.com/resource/pubmed/chemical/Oxidoreductases, N-Demethylating, http://linkedlifedata.com/resource/pubmed/chemical/Protein Sorting Signals, http://linkedlifedata.com/resource/pubmed/chemical/Recombinant Proteins, http://linkedlifedata.com/resource/pubmed/chemical/dnaK protein, E coli, http://linkedlifedata.com/resource/pubmed/chemical/trimethylamine dehydrogenase, http://linkedlifedata.com/resource/pubmed/chemical/twin-arginine translocase complex...
pubmed:status
MEDLINE
pubmed:month
Mar
pubmed:issn
0022-2836
pubmed:author
pubmed:issnType
Print
pubmed:day
30
pubmed:volume
367
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
715-30
pubmed:dateRevised
2010-11-18
pubmed:meshHeading
pubmed:year
2007
pubmed:articleTitle
An essential role for the DnaK molecular chaperone in stabilizing over-expressed substrate proteins of the bacterial twin-arginine translocation pathway.
pubmed:affiliation
School of Chemical and Biomolecular Engineering, Cornell University, Ithaca, NY 14853, USA.
pubmed:publicationType
Journal Article, Research Support, U.S. Gov't, Non-P.H.S., Research Support, Non-U.S. Gov't, Research Support, N.I.H., Extramural