Abstract
We report evidence that ribosomal protein S1 and nucleic acid-binding protein Hfq copurify in molar ratios with RNA polymerase (RNAP). Purified S1 associates independently with RNAP, and Hfq binding to polymerase occurs in the presence of S1. Looking for a functional role of the RNAP-S1-Hfq association, we studied the effects of S1 and Hfq on transcription and coupled transcription-translation. S1 was capable of significant stimulation of the RNAP transcriptional activity from a number of promoters; the stimulatory effect was observed on linear as well as supercoiled DNA templates. In addition, we present biochemical and genetic evidence of ATPase activity associated with the Sm-like hexameric nucleic acid-binding protein Hfq. The limited sequence homology between Hfq and known ATP-utilizing enzymes suggests a new class of ATPases.
MeSH terms
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Adenosine Triphosphatases / metabolism*
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Amino Acid Sequence
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Bacterial Proteins / genetics
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Bacterial Proteins / metabolism*
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Blotting, Western
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DNA-Directed RNA Polymerases / genetics
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DNA-Directed RNA Polymerases / metabolism*
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Escherichia coli / enzymology*
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Escherichia coli / metabolism
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Host Factor 1 Protein / genetics
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Host Factor 1 Protein / metabolism*
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Molecular Sequence Data
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Plasmids
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Protein Binding
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Protein Biosynthesis*
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RNA, Bacterial / metabolism
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RNA, Messenger / genetics*
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RNA, Messenger / metabolism
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Recombinant Proteins / isolation & purification
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Recombinant Proteins / metabolism
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Ribonucleoproteins, Small Nuclear / genetics
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Ribonucleoproteins, Small Nuclear / metabolism
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Ribosomal Proteins / genetics
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Ribosomal Proteins / metabolism*
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Ribosomes / metabolism
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Sequence Homology, Amino Acid
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Sigma Factor / metabolism
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Transcription, Genetic
Substances
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Bacterial Proteins
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Host Factor 1 Protein
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RNA, Bacterial
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RNA, Messenger
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Recombinant Proteins
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Ribonucleoproteins, Small Nuclear
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Ribosomal Proteins
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Sigma Factor
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ribosomal protein S1
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DNA-Directed RNA Polymerases
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Adenosine Triphosphatases