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Prolyl isomerases in a minimal cell. Catalysis of protein folding by trigger factor from Mycoplasma genitalium.
Eur J Biochem. 2000 Jun; 267(11):3270-80.EJ

Abstract

Peptidyl-prolyl cis/trans isomerases (PPIases) catalyze the isomerization of prolyl peptide bonds. Distinct families of this class of enzymes are involved in protein folding in vitro, whereas their significance in free living organisms is not known. Previously, we inspected the smallest known genome of a self-replicating organism and found that Mycoplasma genitalium is devoid of all known PPIases except the trigger factor. Despite the extensive sequence information becoming available, most genes remain hypothetical and enzyme activities in many species have not been assigned to an open reading frame. Therefore, we studied the PPIase activity in crude extracts of M. genitalium. We showed that this is solely attributed to a single enzyme activity, the trigger factor. Characterization of this enzyme revealed that its PPIase activity resides in a central 12-kDa domain. Only the complete trigger factor is able to cis/trans isomerize extended peptide substrates, while the PPIase domain alone can not. The N- and the C-terminal domains of the trigger factor seem to function in binding of proteins as substrates, as demonstrated by protein refolding experiments, in which the complete trigger factor catalyzed protein refolding towards a model protein 500-fold more efficiently than the isolated central PPIase domain. Protein modeling studies suggest that the PPIase domain can fold in a similar way as the PPIase domain of FK506 binding proteins (FKBPs), one class of PPIases, despite only very limited sequence homology. Differences at the active site explain why this enzyme is not inhibited by FK506 in contrast with FKBPs. Trigger factor expressed in Escherichia coli confirms its additional chaperone functions, as shown by its association with chaperones GroEL and GroES after induction of misfolding. In contrast, the isolated PPIase-domain lacks any association with chaperones from E. coli. In summary, trigger factor of M. genitalium is the single folding isomerase of this organism, which harbors an enzymatically active PPIase domain with structural homology to FKBPs. Its additional domains confer its ability to be an efficient catalyst of protein folding. The protein folding machinery is conserved and shows a dual function as a chaperone and a prolyl isomerase.

Authors+Show Affiliations

Institut für Pharmakologie und Toxikologie, Universität Erlangen, Germany.No affiliation info availableNo affiliation info availableNo affiliation info availableNo affiliation info availableNo affiliation info availableNo affiliation info available

Pub Type(s)

Comparative Study
Journal Article
Research Support, Non-U.S. Gov't

Language

eng

PubMed ID

10824113

Citation

Bang, H, et al. "Prolyl Isomerases in a Minimal Cell. Catalysis of Protein Folding By Trigger Factor From Mycoplasma Genitalium." European Journal of Biochemistry, vol. 267, no. 11, 2000, pp. 3270-80.
Bang H, Pecht A, Raddatz G, et al. Prolyl isomerases in a minimal cell. Catalysis of protein folding by trigger factor from Mycoplasma genitalium. Eur J Biochem. 2000;267(11):3270-80.
Bang, H., Pecht, A., Raddatz, G., Scior, T., Solbach, W., Brune, K., & Pahl, A. (2000). Prolyl isomerases in a minimal cell. Catalysis of protein folding by trigger factor from Mycoplasma genitalium. European Journal of Biochemistry, 267(11), 3270-80.
Bang H, et al. Prolyl Isomerases in a Minimal Cell. Catalysis of Protein Folding By Trigger Factor From Mycoplasma Genitalium. Eur J Biochem. 2000;267(11):3270-80. PubMed PMID: 10824113.
* Article titles in AMA citation format should be in sentence-case
TY - JOUR T1 - Prolyl isomerases in a minimal cell. Catalysis of protein folding by trigger factor from Mycoplasma genitalium. AU - Bang,H, AU - Pecht,A, AU - Raddatz,G, AU - Scior,T, AU - Solbach,W, AU - Brune,K, AU - Pahl,A, PY - 2000/5/29/pubmed PY - 2000/7/25/medline PY - 2000/5/29/entrez SP - 3270 EP - 80 JF - European journal of biochemistry JO - Eur J Biochem VL - 267 IS - 11 N2 - Peptidyl-prolyl cis/trans isomerases (PPIases) catalyze the isomerization of prolyl peptide bonds. Distinct families of this class of enzymes are involved in protein folding in vitro, whereas their significance in free living organisms is not known. Previously, we inspected the smallest known genome of a self-replicating organism and found that Mycoplasma genitalium is devoid of all known PPIases except the trigger factor. Despite the extensive sequence information becoming available, most genes remain hypothetical and enzyme activities in many species have not been assigned to an open reading frame. Therefore, we studied the PPIase activity in crude extracts of M. genitalium. We showed that this is solely attributed to a single enzyme activity, the trigger factor. Characterization of this enzyme revealed that its PPIase activity resides in a central 12-kDa domain. Only the complete trigger factor is able to cis/trans isomerize extended peptide substrates, while the PPIase domain alone can not. The N- and the C-terminal domains of the trigger factor seem to function in binding of proteins as substrates, as demonstrated by protein refolding experiments, in which the complete trigger factor catalyzed protein refolding towards a model protein 500-fold more efficiently than the isolated central PPIase domain. Protein modeling studies suggest that the PPIase domain can fold in a similar way as the PPIase domain of FK506 binding proteins (FKBPs), one class of PPIases, despite only very limited sequence homology. Differences at the active site explain why this enzyme is not inhibited by FK506 in contrast with FKBPs. Trigger factor expressed in Escherichia coli confirms its additional chaperone functions, as shown by its association with chaperones GroEL and GroES after induction of misfolding. In contrast, the isolated PPIase-domain lacks any association with chaperones from E. coli. In summary, trigger factor of M. genitalium is the single folding isomerase of this organism, which harbors an enzymatically active PPIase domain with structural homology to FKBPs. Its additional domains confer its ability to be an efficient catalyst of protein folding. The protein folding machinery is conserved and shows a dual function as a chaperone and a prolyl isomerase. SN - 0014-2956 UR - https://www.unboundmedicine.com/medline/citation/10824113/Prolyl_isomerases_in_a_minimal_cell__Catalysis_of_protein_folding_by_trigger_factor_from_Mycoplasma_genitalium_ L2 - https://onlinelibrary.wiley.com/resolve/openurl?genre=article&sid=nlm:pubmed&issn=0014-2956&date=2000&volume=267&issue=11&spage=3270 DB - PRIME DP - Unbound Medicine ER -