title: Conformational change of Escherichia coli signal recognition particle Ffh is affected by the functionality of signal peptides of ribose-binding protein.
abstract: We examined the effects of synthetic signal peptides, wild-type (WT) and export-defective mutant (MT) of ribose-binding protein, on the conformational changes of signal recognition particle 54 homologue (Ffh) in Escherichia coli. Upon interaction of Ffh with WT peptide, the intrinsic Tyr fluorescence, the transition temperature of thermal unfolding, and the GTPase activity of Ffh decreased in a peptide concentration-dependent manner, while the emission intensity of 8-anilinonaphthalene-1-sulfonic acid increased. In contrast, the secondary structure of the protein was not affected. Additionally, polarization of fluorescein-labeled WT increased upon association with Ffh. These results suggest that WT peptide induces the unfolded states of Ffh. The WT-mediated conformational change of Ffh was also revealed to be important in the interaction between SecA and Ffh. However, MT had marginal effect on these conformational changes suggesting that the in vivo functionality of signal peptide is important in the interaction with Ffh and concomitant structural change of the protein.
authors.affiliation: Department of Biochemistry, College of Veterinary Medicine, Chonnam National University, Gwangju 500-757, Korea. thahn@chonnam.ac.kr
authors.forename: Taeho
authors.initials: T
authors.lastname: Ahn
authors.forename: Ju Hee
authors.initials: JH
authors.lastname: Ko
authors.forename: Eun Yi
authors.initials: EY
authors.lastname: Cho
authors.forename: Chul-Ho
authors.initials: CH
authors.lastname: Yun
mesh_terms: D000251:Adenosine Triphosphatases / Q000378:metabolism; D000595:Amino Acid Sequence; D001426:Bacterial Proteins / Q000378:metabolism; D002942:Circular Dichroism; D004926:Escherichia coli / Q000378:metabolism*; D029968:Escherichia coli Proteins / Q000737:chemistry* / Q000378:metabolism*; D019793:Fluorescein / Q000378:metabolism; D005454:Fluorescence Polarization; D031541:Fluorescence Resonance Energy Transfer; D020558:GTP Phosphohydrolases / Q000378:metabolism; D007700:Kinetics; D026901:Membrane Transport Proteins / Q000378:metabolism; D008969:Molecular Sequence Data; D033902:Periplasmic Binding Proteins / Q000737:chemistry / Q000378:metabolism*; D011485:Protein Binding; D011487:Protein Conformation; D017510:Protein Folding; D021382:Protein Sorting Signals; D000069816:SEC Translocation Channels; D000081416:SecA Proteins; D018271:Signal Recognition Particle / Q000737:chemistry*; D013696:Temperature; D044366:Transition Temperature; D014364:Tryptophan / Q000378:metabolism
chemical_list: D001426:Bacterial Proteins; D029968:Escherichia coli Proteins; C082931:Ffh protein, E coli; D026901:Membrane Transport Proteins; D033902:Periplasmic Binding Proteins; D021382:Protein Sorting Signals; C028003:RbsB protein, E coli; D000069816:SEC Translocation Channels; D018271:Signal Recognition Particle; D014364:Tryptophan; D000251:Adenosine Triphosphatases; D020558:GTP Phosphohydrolases; D000081416:SecA Proteins; D019793:Fluorescein