Anti-Mannose Binding Lectin (MBL) ELISA Kit for Duck

Function: An anti-sigma factor for extracytoplasmic function (ECF) sigma factor sigma-E (RpoE). ECF sigma factors are held in an inactive form by an anti-sigma factor until released by regulated intramembrane proteolysis (RIP). RIP occurs when an extracytoplasmic signal triggers a concerted proteolytic cascade to transmit information and elicit cellular responses. The membrane-spanning regulatory substrate protein is first cut periplasmically (site-1 protease, S1P, DegS), then within the membrane itself (site-2 protease, S2P, RseP), while cytoplasmic proteases finish degrading the anti-sigma factor, liberating sigma-E. Overexpression of RseA blocks sigma-E from acting, results in cell lysis in stationary phase and temperature-sensitivity above 37 degrees Celsius. Ref.10 Ref.11 Ref.28

Subunit structure: Interacts 1:1 with ECF RNA polymerase sigma-E (RpoE); this inhibits the interaction of sigma-E with the RNA polymerase catalytic core and leads to a decreased expression of sigma-E-regulated genes. Interacts with RseB with 1:1 stoichiometry. The liberated N-terminus (residues 1-108) forms a complex with SspB and RpoE; binding to SspB is competitively inhibited by ssrA-tags, although the 2 proteins bind in opposite directions in SspB's peptide-binding groove. Ref.7 Ref.10 Ref.11 Ref.13 Ref.16 Ref.17 Ref.21 Ref.22 Ref.24 Ref.25 Ref.28 Ref.29 Ref.30

Subcellular location: Cell inner membrane; Single-pass type II membrane protein. Note: Following cleavage by DegS the large fragment of the protein is still in the inner membrane and retains its anti-sigma-E activity. Ref.10 Ref.11 Ref.13 Ref.15

Induction: Transiently induced by cold shock in a PNPase-dependent fashion. Upon stress induction (OMPs or heat shock) decreases in under 3 minutes (at protein level). Part of the rpoE-rseA-rseB-rseC operon. Ref.12 Ref.18 Ref.20

Domain: The N-terminal cytosolic domain interacts with sigma-E, and upon overexpression leads to temperature sensitivity above 37 degrees Celsius and cell lysis in stationary phase. After degradation by RseP residues 77-108 bind to SspB, targeting RseA for degradation by the ClpX-ClpP protease. Ref.7 Ref.10 Ref.11 Ref.17 Ref.22The C-terminal periplasmic domain (residues 169-186) interacts with RseB and is also the target for DegS; RseB and DegS binding sites do not appreciably overlap. Gln-rich regions (residues 162-169, Q1, and 190-200, Q2) contribute to preventing RseP from acting before DegS. Insertion of 8 consecutive Gln residues into a protein lacking Q1 and Q2 restores DegS-depenedence of RseP cleavage. Ref.7 Ref.10 Ref.11 Ref.17 Ref.22

Post-translational modification: Sequentially cleaved by DegS (a site-1 protease) in its periplasmic domain between Val-148 and Ser-149, then by RseP (a site-2 protease) between positions Ala-108 and Cys-109. The N-terminal fragment is then degraded by primarily ClpX-ClpP in an ATP-dependent fashion. Sequential cleavage by DegS, RseP and ClpX-ClpP frees RpoE from RseA. Ref.7 Ref.8 Ref.9 Ref.12 Ref.14 Ref.15 Ref.17 Ref.19 Ref.24 Ref.26 Ref.28

Disruption phenotype: About 10-fold increased sigma-E activity. Neither sigma-E nor RseB associate with the inner membrane. Ref.10 Ref.11 Ref.13

Sequence similarities: Belongs to the RseA family.

Caution: Ref.11 mis-identifies Trp-33 as residue 32.In vitro (Ref.9) and in vivo (Ref.27) results on the importance of the identity of residue 148 for cleavage by RseP differ.

Sequence caution: The sequence D13169 differs from that shown. Reason: Frameshift at position 75.