A complex signaling module governs the activity of MalT, the prototype of an emerging transactivator family.
MalT, the specific activator of the maltose regulon, is the prototype of a family of high-molecular-mass ATP-binding bacterial transcription activators. On binding of its two positive effectors, the inducer maltotriose and ATP, MalT oligomerizes to an active state competent for promoter binding and transcription activation. In addition to its previously known DNA-binding domain, limited proteolysis showed that MalT contains three other domains, the boundaries of which were accurately delimited by N-terminal microsequencing. The N-terminal domain alone binds ATP. Maltotriose binding involves an extended region corresponding to domains 2 and 3, although weak binding to domain 3 alone was also observed. Moreover, maltotriose binding induces a conformational shift involving a movement of both domains 1 and 3 with respect to domain 2, leading to the active form of the protein. Sequence examination of the MalT homologues suggests that these three domains might constitute a signaling module.
Danot
O
O
Unité de Génétique Moléculaire, Centre National de la Recherche Scientifique, Unité de Recherche Associée 1149, Institut Pasteur, 25 Rue du Dr. Roux, 75724 Paris Cedex 15, France. olivdano@pasteur.fr
D000244:Adenosine Diphosphate / Q000378:metabolism; D000255:Adenosine Triphosphate / Q000378:metabolism; D000266:Adenylyl Imidodiphosphate / Q000378:metabolism; D000494:Allosteric Regulation; D001426:Bacterial Proteins / Q000737:chemistry / Q000235:genetics / Q000502:physiology*; D001665:Binding Sites; D004269:DNA, Bacterial / Q000378:metabolism; D004268:DNA-Binding Proteins / Q000737:chemistry / Q000235:genetics / Q000502:physiology*; D019286:Endopeptidase K / Q000378:metabolism; D004926:Escherichia coli / Q000235:genetics / Q000378:metabolism; D029968:Escherichia coli Proteins; D008024:Ligands; D005810:Multigene Family; D010446:Peptide Fragments / Q000378:metabolism; D010449:Peptide Mapping; D011401:Promoter Regions, Genetic; D011485:Protein Binding; D011487:Protein Conformation / Q000187:drug effects; D017434:Protein Structure, Tertiary; D011993:Recombinant Fusion Proteins / Q000737:chemistry / Q000378:metabolism; D018085:Regulon; D017386:Sequence Homology, Amino Acid; D013329:Structure-Activity Relationship; D015534:Trans-Activators / Q000737:chemistry / Q000235:genetics / Q000502:physiology*; D014157:Transcription Factors; D015533:Transcriptional Activation / Q000187:drug effects*; D014312:Trisaccharides / Q000378:metabolism / Q000494:pharmacology; D014357:Trypsin / Q000378:metabolism
D001426:Bacterial Proteins; D004269:DNA, Bacterial; D004268:DNA-Binding Proteins; D029968:Escherichia coli Proteins; D008024:Ligands; C058976:MalT protein, E coli; D010446:Peptide Fragments; D011993:Recombinant Fusion Proteins; D015534:Trans-Activators; D014157:Transcription Factors; D014312:Trisaccharides; D000266:Adenylyl Imidodiphosphate; D000244:Adenosine Diphosphate; C008317:maltotriose; D000255:Adenosine Triphosphate; D014357:Trypsin; D019286:Endopeptidase K