Rouviere, P. E. & Gross, C. A. SurA, a periplasmic protein with peptidyl-prolyl isomerase activity, participates in the assembly of outer membrane porins. Genes Dev. 10, 3170-3182

Department of Stomatology, University of California, San Francisco 94143-0512, USA.
Genes & Development (Impact Factor: 10.8). 01/1997; 10(24):3170-82. DOI: 10.1101/gad.10.24.3170
Source: PubMed


Little is known about either the process of periplasmic protein folding or how information concerning the folding state in this compartment is communicated. We present evidence that SurA, a periplasmic protein with peptidyl-prolyl isomerase activity, is involved in the maturation and assembly of LamB. LamB is a trimeric outer membrane porin for maltodextrins as well as the bacteriophage lambda receptor in Escherichia coli. We demonstrate that SurA is involved in the conversion of unfolded monomers into a newly identified intermediate in LamB assembly, which behaves as a folded monomer. The absence of SurA blocks the assembly pathway and leads to accumulation of species prior to the folded monomer. These species also accumulate when the stress sigma factor sigmaE is induced by LamB overexpression. We suggest that accumulation of species prior to the generation of folded monomer is a stress signal sensed by sigmaE.

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    • "For PPIases, several catalytic mechanisms have been proposed [26], including (i) stabilization of a more apolar twisted prolyl bond by the hydrophobic enzyme environment, (ii) hydrogen bonding to the prolyl carbonyl oxygen by an enzyme bound water molecule, (iii) nucleophilic catalysis, (iv) protonation of the imide nitrogen, and (v) electrostatic transition-state stabilization. Proteins such as SurA [27], FkpA [28] [29], trigger factor [30] [31] [32], and MtFKBP17 [33] comprise both PPIase and chaperone function located on two different domains. These two domains , however, act synergistically thereby leading to a protein-folding helper enzymes with high catalytic efficiency. "
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    ABSTRACT: During protein folding reactions toward the native structure, short-lived intermediate states can be populated. Such intermediates expose hydrophobic patches and can self-associate leading to non-productive protein misfolding. A major focus of current research is the characterization of short-lived intermediates and how molecular chaperones enable productive folding. Real-time NMR spectroscopy, together with the development of advanced methods, is reviewed here and the potential these methods have to characterize intermediate states as well as interactions with molecular chaperone proteins at single-residue resolution is highlighted. Various chaperone interactions can guide the protein folding reaction and thus are important for protein structure formation, stability, and activity of their substrates. Chaperone-assisted protein folding, characterization of intermediates, and their molecular interactions using real-time NMR spectroscopy will be discussed. Additionally, recent advances in NMR methods employed for characterization of high-energy intermediates will be discussed. Real-time NMR combines high-resolution with kinetic information of protein reactions, which can be employed not only for protein folding studies and the characterization of folding intermediates but also to investigate the molecular mechanisms of assisted protein folding. Real-time NMR spectroscopy remains an effective tool to reveal structural details about the interaction between chaperones and transient intermediates. Methodologically, it provides in-depth understanding of how kinetic intermediates and their thermodynamics contribute to the protein folding reaction. This review summarizes the most recent advances in this field. This article is part of a Special Issue entitled Proline-directed Foldases: Cell Signaling Catalysts and Drug Targets. Copyright © 2014. Published by Elsevier B.V.
    Full-text · Article · Dec 2014 · Biochimica et Biophysica Acta (BBA) - General Subjects
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    • "Here, we examined whether parvulin domains can also be transformed into folding enzymes by fusing them with chaperone domains. The SurA protein of Escherichia coli is a periplasmic protein and participates in the maturation of outer membrane proteins [17] [18] [19]. It consists of two parvulin domains (Par1 and Par2) and a chaperone domain [20] [21]. "
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    ABSTRACT: Parvulins are small prolyl isomerases and serve as catalytic domains of folding enzymes. SurA from the periplasm of Escherichia coli consists of an inactive (Par1) and an active (Par2) parvulin domain as well as a chaperone domain. In the absence of the chaperone domain, the folding activity of Par2 is virtually abolished. We created a chimeric protein by inserting the chaperone domain of SlyD, an unrelated folding enzyme from the FKBP family, into a loop of the isolated Par2 domain of SurA. This increased its folding activity 450-fold to a value higher than the activity of SurA, in which Par2 is linked with its natural chaperone domain. In the presence of both the natural and the foreign chaperone domain, the folding activity of Par2 was 1500-fold increased. Related and unrelated chaperone domains thus are similarly efficient in enhancing the folding activity of the prolyl isomerase Par2. A sequence analysis of various chaperone domains suggests that clusters of exposed methionine residues in mobile chain regions might be important for a generic interaction with unfolded protein chains. This binding is highly dynamic to allow frequent transfer of folding protein chains between chaperone and catalytic domains.
    Preview · Article · Jul 2013 · Journal of Molecular Biology
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    • "In L. lactis, by analogy with SlrA protein, PpiA protein could play a significant role under specific, although not yet identified, conditions. The understanding of PPIase function and their conditions of activity in vivo requires the knowledge of their substrates, but only very few substrates of PPIases, all of the parvulin family, are known: i) L. lactis PrtP, the envelope proteinase, needs PrtM to be active and able to degrade caseins, and finally to allow growth on milk [38] (and reference therein) [39]; ii) E. coli pilins require SurA to assemble into functional pili that are important invasion factors in virulent strains [3], [4], [5], [6], [59]; and iii) B. subtilis penicillin binding proteins, including the essential PBP2a protein, are dependent on PrsA for their folding, which makes PrsA itself an essential protein [10]. Whether PpiA protein contibutes to protein folding in L. lactis cell envelope will deserve further investigation. "
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    ABSTRACT: Protein folding in the envelope is a crucial limiting step of protein export and secretion. In order to better understand this process in Lactococcus lactis, a lactic acid bacterium, genes encoding putative exported folding factors like Peptidyl Prolyl Isomerases (PPIases) were searched for in lactococcal genomes. In L. lactis, a new putative membrane PPIase of the cyclophilin subfamily, PpiA, was identified and characterized. ppiA gene was found to be constitutively expressed under normal and stress (heat shock, H(2)O(2)) conditions. Under normal conditions, PpiA protein was synthesized and released from intact cells by an exogenously added protease, showing that it was exposed at the cell surface. No obvious phenotype could be associated to a ppiA mutant strain under several laboratory conditions including stress conditions, except a very low sensitivity to H(2)O(2). Induction of a ppiA copy provided in trans had no effect i) on the thermosensitivity of an mutant strain deficient for the lactococcal surface protease HtrA and ii) on the secretion and stability on four exported proteins (a highly degraded hybrid protein and three heterologous secreted proteins) in an otherwise wild-type strain background. However, a recombinant soluble form of PpiA that had been produced and secreted in L. lactis and purified from a culture supernatant displayed both PPIase and chaperone activities. Although L. lactis PpiA, a protein produced and exposed at the cell surface under normal conditions, displayed a very moderate role in vivo, it was found, as a recombinant soluble form, to be endowed with folding activities in vitro.
    Full-text · Article · Mar 2012 · PLoS ONE
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