Inventory of the GH70 enzymes encoded by Leuconostoc citreum NRRL B‐1299 – identification of three novel α‐transglucosylases. (8th April 2015)

• Record Type: Journal Article
• Authors: Passerini, Delphine; Vuillemin, Marlène; Ufarté, Lisa; Morel, Sandrine; Loux, Valentin; Fontagné‐Faucher, Catherine; Monsan, Pierre; Remaud‐Siméon, Magali; Moulis, Claire
• Is Part Of: FEBS journal. Volume 282:Number 11(2015)
• Page Start: 2115
• Page End: 2130
• Publication Date: 2015-04-08
• Subjects: Biochemistry -- Periodicals; Molecular biology -- Periodicals; Pathology, Molecular -- Periodicals; 572
• DOI: 10.1111/febs.13261
• Languages: English
• ISSNs: 1742-464X

Abstract

<abstract abstract-type="main" id="febs13261-abs-0001"> <title> <x xml:space="preserve">Abstract</x> </title> <p> <italic>Leuconostoc citreum </italic>NRRL B‐1299 has long been known to produce α‐glucans containing both α‐(1→6) and α‐(1→2) linkages, which are synthesized by α‐transglucosylases of the GH70 family. We sequenced the genome of <italic>Leuconostoc citreum </italic>NRRL B‐1299 to identify the full inventory of GH70 enzymes in this strain. Three new genes (<italic>brsA</italic>, <italic> dsrM</italic> and <italic>dsrDP</italic>) putatively encoding GH70 enzymes were identified. The corresponding recombinant enzymes were characterized. Branching sucrase A (BRS‐A) grafts linear α‐(1→6) dextran with α‐(1→2)‐linked glucosyl units, and is probably involved in the α‐(1→2) branching of <italic>L. citreum </italic>NRRL B‐1299 dextran. This is the first report of a naturally occurring α‐(1→2) branching sucrase. DSR‐M and DSR‐DP are dextransucrases that are specific for α‐(1→6) linkage synthesis and mainly produce oligomers or short dextrans with molar masses between 580 and 27 000 g·mol<sup>−1</sup>. In addition, DSR‐DP contains sequences that diverge from the consensus sequences that are typically present in enzymes that synthesize linear dextran. Comparison of the genome with five other <italic>L. citreum</italic> genomes further revealed that <italic>dsrDP is</italic> unique to <italic>L. citreum </italic>NRRL B‐1299. The presence of this gene in a prophage represents the first evidence of phage‐mediated horizontal transfer of genes encoding such enzymes in lactic acid bacteria. Finally, <italic>brsA</italic> and <italic>dsrM</italic> are located in a chromosomal region in which genes encoding strain‐specific GH70 enzymes are consistently located. This region may be a good target on which to focus in order to rapidly evaluate the diversity of GH70 enzymes in <italic>L. citreum</italic> strains.</p> </abstract>