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![[Figure 1]](gm5029fig1mag.jpg)
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Figure 1
Crystal structure of M. tuberculosis σK in complex with its negative regulator RskA. (a) The transmembrane anti-σ factor RskA negatively regulates and localizes M. tuberculosis σK. (b) The crystal structure of σK (yellow) in complex with the cytosolic anti-σ domain of RskA (blue) reveals that RskA binding occludes the RNA polymerase interacting and DNA-binding surfaces of σK. The crystal structure reveals a disulfide in domain 4 of σK. (c) Superposition of σK2 on E. coli σE2 (structure obtained from the E. coli σE–RsrA complex; PDB entry 1or7; Campbell et al., 2003  ) and R. sphaeroides σE2 (from the R. sphaeroides σE–ChrR complex; PDB entry 2z2s; Campbell et al., 2007). (d) Superposition of the ASDs of M. tuberculosis RskA and RslA (Thakur et al., 2010) on the ASD of R. sphaeroides ChrR (Campbell et al., 2007). (e) Superposition of σK4 on σE4 of R. sphaeroides (PDB entry 2z2s; Campbell et al., 2007) and M. tuberculosis σL4 (structure obtained from the M. tuberculosis σL4–RslA complex; PDB entry 3hug; Thakur et al., 2010). (f) The σK–RskAcyto complex reveals extensive interactions between the structured domains of σK and RskAcyto that effectively occlude the DNA-binding and RNA polymerase interacting regions of σK. This interface mostly involves van der Waals interactions, with few polar interactions. |
![[Figure 1]](gm5029fig1.jpg)
 | STRUCTURAL BIOLOGY |
ISSN: 2059-7983
