5MTU

Maltodextrin binding protein MalE1 from L. casei BL23 bound to alpha-cyclodextrin

Summary for 5MTU

• Entry DOI: 10.2210/pdb5mtu/pdb
• Related: 5M28
• Related PRD ID: PRD_900015
• Descriptor: MalE1, Cyclohexakis-(1-4)-(alpha-D-glucopyranose) (3 entities in total)
• Functional Keywords: carbohydrate binding protein, lactobacillus casei, sugar binding protein
• Biological source: Lactobacillus casei BL23
• Total number of polymer chains: 1
• Total formula weight: 41495.59

Authors

Homburg, C.,Bommer, M.,Wuttge, S.,Hobe, C.,Beck, S.,Dobbek, H.,Deutscher, J.,Licht, A.,Schneider, E. (deposition date: 2017-01-10, release date: 2017-07-05, Last modification date: 2024-05-08)

Primary citation

Homburg, C.,Bommer, M.,Wuttge, S.,Hobe, C.,Beck, S.,Dobbek, H.,Deutscher, J.,Licht, A.,Schneider, E.
Inducer exclusion in Firmicutes: insights into the regulation of a carbohydrate ATP binding cassette transporter from Lactobacillus casei BL23 by the signal transducing protein P-Ser46-HPr.
Mol. Microbiol., 105:25-45, 2017

PubMed Abstract: Catabolite repression is a mechanism that enables bacteria to control carbon utilization. As part of this global regulatory network, components of the phosphoenolpyruvate:carbohydrate phosphotransferase system inhibit the uptake of less favorable sugars when a preferred carbon source such as glucose is available. This process is termed inducer exclusion. In bacteria belonging to the phylum Firmicutes, HPr, phosphorylated at serine 46 (P-Ser46-HPr) is the key player but its mode of action is elusive. To address this question at the level of purified protein components, we have chosen a homolog of the Escherichia coli maltose/maltodextrin ATP-binding cassette transporter from Lactobacillus casei (MalE1-MalF1G1K1 ) as a model system. We show that the solute binding protein, MalE1, binds linear and cyclic maltodextrins but not maltose. Crystal structures of MalE1 complexed with these sugars provide a clue why maltose is not a substrate. P-Ser46-HPr inhibited MalE1/maltotetraose-stimulated ATPase activity of the transporter incorporated in proteoliposomes. Furthermore, cross-linking experiments revealed that P-Ser46-HPr contacts the nucleotide-binding subunit, MalK1, in proximity to the Walker A motif. However, P-Ser46-HPr did not block binding of ATP to MalK1. Together, our findings provide first biochemical evidence that P-Ser-HPr arrests the transport cycle by preventing ATP hydrolysis at the MalK1 subunits of the transporter.

PubMed: 28370477
DOI: 10.1111/mmi.13680

Experimental method

X-RAY DIFFRACTION (0.999 Å)