Structural basis of the membrane intramolecular transacylase reaction responsible for lyso-form lipoprotein synthesis

Olatunji, Samir, Bowen, Katherine, Huang, Chia-Ying, Weichert, Dietmar, Singh, Warispreet, Tikhonova, Irina G., Scanlan, Eoin M., Olieric, Vincent and Caffrey, Martin (2021) Structural basis of the membrane intramolecular transacylase reaction responsible for lyso-form lipoprotein synthesis. Nature Communications, 12 (1). ISSN 2041-1723

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Official URL: https://doi.org/10.1038/s41467-021-24475-0

Abstract

Abstract: Lipoproteins serve diverse functions in the bacterial cell and some are essential for survival. Some lipoproteins are adjuvants eliciting responses from the innate immune system of the host. The growing list of membrane enzymes responsible for lipoprotein synthesis includes the recently discovered lipoprotein intramolecular transacylase, Lit. Lit creates a lipoprotein that is less immunogenic, possibly enabling the bacteria to gain a foothold in the host by stealth. Here, we report the crystal structure of the Lit enzyme from Bacillus cereus and describe its mechanism of action. Lit consists of four transmembrane helices with an extracellular cap. Conserved residues map to the cap-membrane interface. They include two catalytic histidines that function to effect unimolecular transacylation. The reaction involves acyl transfer from the sn-2 position of the glyceryl moiety to the amino group on the N-terminal cysteine of the substrate via an 8-membered ring intermediate. Transacylation takes place in a confined aromatic residue-rich environment that likely evolved to bring distant moieties on the substrate into proximity and proper orientation for catalysis.

Item Type: Article
Additional Information: Funding information: We thank L Figur, M Elhantati and J Bond for assistance with protein production and purification, and with crystallisation trials; synchrotron facility scientists at the Diamond Light Source (beamline I24) and the Swiss Light Source (beamlines X06SA and X10SA) for assistance and support, and past and present members of the Membrane Structural and Functional Biology group for assorted contributions to the study. This work was supported in part by Science Foundation Ireland awards 16/IA/4435 (M.C.) and 15/CDA/3310 (E.M.S. and K.B.), an Irish Research Council fellowship GOIPG/2016/1238 (K.B.), a German Research Foundation grant WE 6084/1-1 (D.W.), by the European Union’s Horizon 2020 research and innovation programme under the Marie-Skłodowska-Curie grant agreement No. 701647 (C.-Y.H.) and the Northern Ireland Department of Agriculture, Environment and Rural Affairs Award No. 05935-NAGpro (I.G.T.). W.S. acknowledges the support by Research England’s Expanding Excellence in England (E3) Fund. This project made use of computational time on Kelvin-2 (grant no. EP/T022175/1); and JADE granted via the UK High-End Computing Consortium for Biomolecular Simulation, HECBioSim (hecbiosim.ac.uk), supported by EPSRC (grant no. EP/R029407/1).
Uncontrolled Keywords: X-ray crystallography, Lipoproteins, Enzyme mechanisms, Bacterial immune evasion
Subjects: C100 Biology
C700 Molecular Biology, Biophysics and Biochemistry
C900 Others in Biological Sciences
Department: Faculties > Health and Life Sciences > Applied Sciences
Depositing User: Rachel Branson
Date Deposited: 13 Jul 2021 14:36
Last Modified: 13 Jul 2021 14:45
URI: http://nrl.northumbria.ac.uk/id/eprint/46670

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