Crystal structure of Mycobacterium tuberculosis LrpA, a leucine-responsive global regulator associated with starvation response.
The bacterial leucine-responsive regulatory protein (Lrp) is a global transcriptional regulator that controls the expression of many genes during starvation and the transition to stationary phase. The Mycobacterium tuberculosis gene Rv3291c encodes a 150-amino acid protein (designated here as Mtb LrpA) with homology with Escherichia coli Lrp. The crystal structure of the native form of Mtb LrpA was solved at 2.1 A. The Mtb LrpA structure shows an N-terminal DNA-binding domain with a helix-turn-helix (HTH) motif, and a C-terminal regulatory domain. In comparison to the complex of E. coli AsnC with asparagine, the effector-binding pocket (including loop 100-106) in LrpA appears to be largely preserved, with hydrophobic substitutions consistent with its specificity for leucine. The effector-binding pocket is formed at the interface between adjacent dimers, with an opening to the core of the octamer as in AsnC, and an additional substrate-access channel opening to the outer surface of the octamer. Using electrophoretic mobility shift assays, purified Mtb LrpA protein was shown to form a protein-DNA complex with the lat promoter, demonstrating that the lat operon is a direct target of LrpA. Using computational analysis, a putative motif is identified in this region that is also present upstream of other operons differentially regulated under starvation. This study provides insights into the potential role of LrpA as a global regulator in the transition of M. tuberculosis to a persistent state.
Reddy
Manchi C M
MC
Department of Biochemistry and Biophysics, Texas A and M University, College Station, Texas 77843-2128, USA.
Gokulan
Kuppan
K
Jacobs
William R
WR
Ioerger
Thomas R
TR
Sacchettini
James C
JC
D000595:Amino Acid Sequence; D001426:Bacterial Proteins / Q000737:chemistry* / Q000235:genetics; D001483:Base Sequence; D016384:Consensus Sequence; D003470:Culture Media; D015964:Gene Expression Regulation, Bacterial; D018257:Helix-Loop-Helix Motifs; D006706:Homeostasis; D051756:Leucine-Responsive Regulatory Protein / Q000737:chemistry* / Q000235:genetics; D008958:Models, Molecular; D008969:Molecular Sequence Data; D009169:Mycobacterium tuberculosis / Q000737:chemistry* / Q000235:genetics / Q000254:growth & development; D011487:Protein Conformation; D014158:Transcription, Genetic
D001426:Bacterial Proteins; D003470:Culture Media; C499616:LrpA protein, bacteria; D051756:Leucine-Responsive Regulatory Protein