Diverse sequences are functional at the C-terminus of the E. coli periplasmic chaperone SurA

Qian Chai, Brent Ferrell, Meng Zhong, Xinyi Zhang, Cui Ye, Yinan Wei

Research output: Contribution to journalArticlepeer-review

8 Scopus citations


SurA is a major periplasmic molecular chaperone in Escherichia coli and has been shown to assist the biogenesis of several outer membrane proteins. The C-terminal fragment of SurA folds into a short β-strand, which forms a small three-stranded anti-parallel β-sheet module with the N-terminal β-hairpin. We found that the length of the C-terminal fragment, rather than its exact amino acid composition, had a big impact on SurA function. To investigate the determinant factor of the C-terminal sequence, we created a library of SurA constructs randomized in the last 10 residues. We screened the library and randomly analyzed 19 constructs that displayed SurA activity. The C-termini of these constructs shared little sequence similarity, except that β-strand-forming residues were preferentially enriched. Three SurA constructs were expressed and purified for structural characterization. Circular dichroism and fluorescence spectroscopy analyses revealed that their structures were similar to the structure of the wild-type SurA. Our results suggest that for scaffolding purpose proteins may tolerate various sequences provided certain general requirements such as hydrophobicity and secondary structure propensity are satisfied. Furthermore, the sequence tolerance of SurA at the C-terminus indicates that this area is not likely to be involved in substrate binding.

Original languageEnglish
Pages (from-to)111-116
Number of pages6
JournalProtein Engineering, Design and Selection
Issue number4
StatePublished - Apr 2014

Bibliographical note

Funding Information:
This work was supported by the National Science Foundation (MCB 1158036 to Y.W.) and NASA EPSCoR program (WKURF 516212 and NNX10AV39A to Y.W.).


  • mutation
  • periplasmic molecular chaperone
  • random sequence library
  • sequence diversity

ASJC Scopus subject areas

  • Biotechnology
  • Bioengineering
  • Biochemistry
  • Molecular Biology


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