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Identification of bacterial transporters for hydroxyalkylcysteines: a novel target for reducing axillary malodour

Reference	BB/H016201/1
Principal Investigator / Supervisor	Professor Gavin Thomas
Co-Investigators / Co-Supervisors	Dr Alexander James
Institution	University of York
Department	Biology
Funding type	Skills
Value (£)	75,281
Status	Completed
Type	Training Grants
Start date	01/10/2010
End date	30/09/2014
Duration	48 months

Abstract

unavailable

Summary

The production of thioalcohols by commensal skin bacteria is an important component of the malodour produced by microbial metabolism of natural apocrine gland secretions in the human axilla (underarm). These compounds are produced via the cleavage of hydroxyalkylcysteine precursors to pyruvate, ammonia and thioalcohols by an intracellular bacterial enzyme, C-S beta-lyase (CSL), which has been characterised both genetically and biochemically in the Gram-positive odour-forming axillary microorganism Corynebacterium jeikeium K411 (James et al., 2007). While the CSL reaction occurs within the bacterial cell, the malodorous thioalcohols are known to exist extracellularly. There is thus a requirement both for the hydroxyalkylcysteine substrates to be taken up from the environment by the bacteria, and the thioalcohol products to be released back into the environment. Neither of these processes is understood at the molecular level in any bacterium, although they clearly provide attractive targets for intervention, aimed at minimising thioalcohol production by commensal bacteria, and hence reduced axillary malodour. In this project we wish to understand the mechanism of uptake and efflux of these important compounds by bacterial cells using a range of complementary techniques. Further to the above, there is recent evidence that the true thioalcohol precursors, as secreted by the apocrine gland, are in fact hydroxyalkylcysteinylglycines, originating from glutathione adducts. It is claimed that thioalcohol release from these conjugates requires the sequential action of a dipeptidase and CSL, although it is unclear whether the former enzyme is expressed intra- or extracellularly (Emter & Natsch, 2008). While there are no known transporters for hydroxyalkylcysteines, these compounds structurally resemble dipeptides and, by definition, also contain a single cysteine residue. In addition, as highlighted above, it is unclear whether the precursor molecules imported by axillary bacteria are hydroxyalkylcysteines, hydroxyalkylcysteinylglycines, themselves dipeptide conjugates, or a combination thereof. Therefore, in this project, we will develop transporter deficient (TD) E. coli strains for dipeptides, glutathione and cysteine, which we will then use for complementation analysis with a range of putative peptide and cysteine transporters cloned from Corynebacterium jeikeium K411, to identify the molecular basis of transport of these substrates in this organism. We will also target orthologous genes from the closely-related and highly genetically-characterised organism C. glutamicum. To determine whether these proteins play any role in uptake of hydroxyalkylcysteines, we will create strains of C. glutamicum disrupted in these genes. The student will then spend time working at Unilever R&D Colworth to characterise the ability of these strains to catabolise hydroxyalkylcysteines and hydroxyalkylcysteinylglycines and, in the process, produce malodorous thioalcohols. Emter R and Natsch A. The sequential action of a dipeptidase and a beta-lyase is required for the release of the human body odorant 3-methyl-3-sulfanylhexan-1-ol from a secreted Cys-Gly-(S) conjugate by Corynebacteria. J Biol Chem 283, 20645-20652 (2008). James AG, Austin C, Hyliands D et al. Microbiological and biochemical origins of human axillary malodour. Proceedings 4th International Symposium, Cosm'ing 2007, Saint-Malo, France (www.cbb-developpement.com/cosming2007), pp 137-147.

Committee	Not funded via Committee
Research Topics	X – not assigned to a current Research Topic
Research Priority	X – Research Priority information not available
Research Initiative	X - not in an Initiative
Funding Scheme	Training Grant - Industrial Case

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