A seven-gene cluster in Ruminiclostridium cellulolyticum is essential for signalization, uptake and catabolism of the degradation products of cellulose hydrolysis - Archive ouverte HAL Accéder directement au contenu
Article Dans Une Revue Biotechnology for Biofuels Année : 2017

A seven-gene cluster in Ruminiclostridium cellulolyticum is essential for signalization, uptake and catabolism of the degradation products of cellulose hydrolysis

Résumé

Background: Like a number of anaerobic and cellulolytic Gram-positive bacteria, the model microorganism Ruminiclostridium cellulolyticum produces extracellular multi-enzymatic complexes called cellulosomes, which efficiently degrade the crystalline cellulose. Action of the complexes on cellulose releases cellobiose and longer cellodextrins but to date, little is known about the transport and utilization of the produced cellodextrins in the bacterium. A better understanding of the uptake systems and fermentation of sugars derived from cellulose could have a major impact in the field of biofuels production. Results: We characterized a putative ABC transporter devoted to cellodextrins uptake, and a cellobiose phosphorylase (CbpA) in R. cellulolyticum. The genes encoding the components of the ABC transporter (a binding protein CuaA and two integral membrane proteins) and CbpA are expressed as a polycistronic transcriptional unit induced in the presence of cellobiose. Upstream, another polycistronic transcriptional unit encodes a two-component system (sensor and regulator), and a second binding protein CuaD, and is constitutively expressed. The products might form a three-component system inducing the expression of cuaABC and cbpA since we showed that CuaR is able to recognize the region upstream of cuaA. Biochemical analysis showed that CbpA is a strict cellobiose phosphorylase inactive on longer cellodextrins; CuaA binds to all cellodextrins (G2-G5) tested, whereas CuaD is specific to cellobiose and presents a higher affinity to this sugar. This results are in agreement with their function in transport and signalization, respectively. Characterization of a cuaD mutant, and its derivatives, indicated that the ABC transporter and CbpA are essential for growth on cellobiose and cellulose. Conclusions: For the first time in a Gram-positive strain, we identified a three-component system and a conjugated ABC transporter/cellobiose phosphorylase system which was shown to be essential for the growth of the model cellulolytic bacterium R. cellulolyticum on cellobiose and cellulose. This efficient and energy-saving system of transport and phosphorolysis appears to be the major cellobiose utilization pathway in R. cellulolyticum, and seems well adapted to cellulolytic life-style strain. It represents a new way to enable engineered strains to utilize cellodextrins for the production of biofuels or chemicals of interest from cellulose.
Fichier principal
Vignette du fichier
Fosses et al 2017.pdf (1.58 Mo) Télécharger le fichier
Origine : Fichiers éditeurs autorisés sur une archive ouverte
Loading...

Dates et versions

hal-01640052 , version 1 (07-05-2018)

Identifiants

Citer

Aurelie Fosses, Maria Mate, Nathalie Franche, Nian Liu, Yann Denis, et al.. A seven-gene cluster in Ruminiclostridium cellulolyticum is essential for signalization, uptake and catabolism of the degradation products of cellulose hydrolysis. Biotechnology for Biofuels, 2017, 10, ⟨10.1186/s13068-017-0933-7⟩. ⟨hal-01640052⟩
263 Consultations
58 Téléchargements

Altmetric

Partager

Gmail Facebook X LinkedIn More