L‐Rhamnose catabolism in archaea. Issue 4 (18th March 2019)

• Record Type: Journal Article
• Authors: Reinhardt, Andreas; Johnsen, Ulrike; Schönheit, Peter
• Is Part Of: Molecular microbiology. Volume 111:Issue 4(2019)
• Page Start: 1093
• Page End: 1108
• Publication Date: 2019-03-18
• Subjects: Molecular microbiology -- Periodicals; 572.829
• DOI: 10.1111/mmi.14213
• Languages: English
• ISSNs: 0950-382X

Abstract

Summary: The halophilic archaeon Haloferax volcanii utilizesl ‐rhamnose as a sole carbon and energy source. It is shown thatl ‐rhamnose is taken up by an ABC transporter and is oxidatively degraded to pyruvate andl ‐lactate via the diketo‐hydrolase pathway. The genes involved inl ‐rhamnose uptake and degradation form al ‐rhamnose catabolism ( rhc ) gene cluster. The rhc cluster also contains a gene, rhcR, that encodes the transcriptional regulator RhcR which was characterized as an activator of all rhc genes. 2‐keto‐3‐deoxy‐l ‐rhamnonate, a metabolic intermediate ofl ‐rhamnose degradation, was identified as inducer molecule of RhcR. The essential function of rhc genes for uptake and degradation ofl ‐rhamnose was proven by the respective knockout mutants. Enzymes of the diketo‐hydrolase pathway, includingl ‐rhamnose dehydrogenase, l ‐rhamnonolactonase, l ‐rhamnonate dehydratase, 2‐keto‐3‐deoxy‐l ‐rhamnonate dehydrogenase and 2, 4‐diketo‐3‐deoxy‐l ‐rhamnonate hydrolase, were characterized. Further, genes of the diketo‐hydrolase pathway were also identified in the hyperthermophilic crenarchaeota Vulcanisaeta distributa and Sulfolobus solfataricus and selected enzymes were characterized, indicating the presence of the diketo‐hydrolase pathway in these archaea. Together, this is the first comprehensive description ofl ‐rhamnose catabolism in the domain of archaea. Abstract : Here, we present a comprehensive analysis ofl ‐rhamnose catabolism in the halophilic euryarchaeon Haloferax volcanii . In this archaeon, l ‐rhamnose is taken up by an ABC transporter and is degraded via the diketo‐hydrolase pathway that is regulated by the bacterial like transcriptional activator RhcR. Further evidence is presented for the operation of the diketo‐hydrolase pathway in the hyperthermophilic crenarchaeota Sulfolobus solfataricus and Vulcanisaeta distributa .