A new lysine biosynthetic enzyme from a bacterial endosymbiont shaped by genetic drift and genome reduction.

Autor: Gilkes JM; Biomolecular Interaction Centre, School of Biological Sciences, University of Canterbury, Christchurch, New Zealand.; The New Zealand Institute for Plant and Food Research Limited, Lincoln, New Zealand.; Callaghan Innovation, University of Canterbury, Christchurch, New Zealand., Frampton RA; The New Zealand Institute for Plant and Food Research Limited, Lincoln, New Zealand., Board AJ; Biomolecular Interaction Centre, School of Biological Sciences, University of Canterbury, Christchurch, New Zealand., Hudson AO; Rochester Institute of Technology, Thomas H. Gosnell School of Life Sciences, Rochester, New York, USA., Price TG; Biomolecular Interaction Centre, School of Chemical and Physical Sciences, University of Canterbury, Christchurch, New Zealand., Morris VK; Biomolecular Interaction Centre, School of Biological Sciences, University of Canterbury, Christchurch, New Zealand., Crittenden DL; Biomolecular Interaction Centre, School of Chemical and Physical Sciences, University of Canterbury, Christchurch, New Zealand., Muscroft-Taylor AC; Callaghan Innovation, University of Canterbury, Christchurch, New Zealand., Sheen CR; Callaghan Innovation, University of Canterbury, Christchurch, New Zealand., Smith GR; The New Zealand Institute for Plant and Food Research Limited, Lincoln, New Zealand., Dobson RCJ; Biomolecular Interaction Centre, School of Biological Sciences, University of Canterbury, Christchurch, New Zealand.; Bio21 Molecular Science and Biotechnology Institute, Department of Biochemistry and Molecular Biology, University of Melbourne, Parkville, Victoria, Australia.
Jazyk: angličtina
Zdroj: Protein science : a publication of the Protein Society [Protein Sci] 2024 Jul; Vol. 33 (7), pp. e5083.
DOI: 10.1002/pro.5083
Abstrakt: The effect of population bottlenecks and genome reduction on enzyme function is poorly understood. Candidatus Liberibacter solanacearum is a bacterium with a reduced genome that is transmitted vertically to the egg of an infected psyllid-a population bottleneck that imposes genetic drift and is predicted to affect protein structure and function. Here, we define the function of Ca. L. solanacearum dihydrodipicolinate synthase (CLsoDHDPS), which catalyzes the committed branchpoint reaction in diaminopimelate and lysine biosynthesis. We demonstrate that CLsoDHDPS is expressed in Ca. L. solanacearum and expression is increased ~2-fold in the insect host compared to in planta. CLsoDHDPS has decreased thermal stability and increased aggregation propensity, implying mutations have destabilized the enzyme but are compensated for through elevated chaperone expression and a stabilized oligomeric state. CLsoDHDPS uses a ternary-complex kinetic mechanism, which is to date unique among DHDPS enzymes, has unusually low catalytic ability, but an unusually high substrate affinity. Structural studies demonstrate that the active site is more open, and the structure of CLsoDHDPS with both pyruvate and the substrate analogue succinic-semialdehyde reveals that the product is both structurally and energetically different and therefore evolution has in this case fashioned a new enzyme. Our study suggests the effects of genome reduction and genetic drift on the function of essential enzymes and provides insights on bacteria-host co-evolutionary associations. We propose that bacteria with endosymbiotic lifestyles present a rich vein of interesting enzymes useful for understanding enzyme function and/or informing protein engineering efforts.
(© 2024 The Author(s). Protein Science published by Wiley Periodicals LLC on behalf of The Protein Society.)
Databáze: MEDLINE
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