Biochemical and spectroscopic characterization of purified Latex Clearing Protein (Lcp) from newly isolated rubber degrading Rhodococcus rhodochrous strain RPK1 reveals novel properties of Lcp

BMC Microbiology

Research Article

Jakob Birke¹  Wolf Röther¹  Dieter Jendrossek¹  Sirimaporn Watcharakul²  Kamontam Umsakul³  Brian Hodgson³ 

[1] Institute of Microbiology, University of Stuttgart, Allmandring 31, 70569, Stuttgart, Germany;Institute of Microbiology, University of Stuttgart, Allmandring 31, 70569, Stuttgart, Germany;Prince of Songkla University, Songkla, Thailand;Prince of Songkla University, Songkla, Thailand;

关键词: Latex clearing protein (Lcp);    Rubber oxygenase;    Dioxygenase;    Rhodococcus;    Biodegradation;   

DOI  :  10.1186/s12866-016-0703-x

 received in 2016-01-19, accepted in 2016-05-10,  发布年份 2016

来源: Springer

【 摘 要 】

BackgroundBiodegradation of rubber (polyisoprene) is initiated by oxidative cleavage of the polyisoprene backbone and is performed either by an extracellular rubber oxygenase (RoxA) from Gram-negative rubber degrading bacteria or by a latex clearing protein (Lcp) secreted by Gram-positive rubber degrading bacteria. Only little is known on the biochemistry of polyisoprene cleavage by Lcp and on the types and functions of the involved cofactors.ResultsA rubber-degrading bacterium was isolated from the effluent of a rubber-processing factory and was taxonomically identified as a Rhodococcus rhodochrous species. A gene of R. rhodochrous RPK1 that coded for a polyisoprene-cleaving latex clearing protein (lcpRr) was identified, cloned, expressed in Escherichia coli and purified. Purified LcpRr had a specific activity of 3.1 U/mg at 30 °C and degraded poly(1,4-cis-isoprene) to a mixture of oligoisoprene molecules with terminal keto and aldehyde groups. The pH optimum of LcpRr was higher (pH 8) than for other rubber-cleaving enzymes (≈ pH 7). UVvis spectroscopic analysis of LcpRr revealed a cytochrome-specific absorption spectrum with an additional feature at long wavelengths that has not been observed for any other rubber-cleaving enzyme. The presence of one b-type haem in LcpRr as a co-factor was confirmed by (i) metal analysis, (ii) solvent extraction, (iii) bipyridyl assay and (iv) detection of haem-b specific m/z values via mass-spectrometry.ConclusionsOur data point to substantial differences in the active sites of Lcp proteins obtained from different rubber degrading bacteria.

【 授权许可】

CC BY   
© Watcharakul et al. 2016