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Query: UMLS:C0348321 (Haemophilus)
 15,372 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The rhomboid family of serine proteases occurs in all domains of life. Its members contain at least six hydrophobic membrane-spanning helices, with an active site serine located deep within the hydrophobic interior of the plasma membrane. The model member GlpG from Escherichia coli is heavily studied through engineered mutant forms, varied model substrates, and multiple X-ray crystal studies, yet its relationship to endogenous substrates is not well understood. Here we describe an apparent membrane anchoring C-terminal homology domain that appears in numerous genera including Shewanella, Vibrio, Acinetobacter, and Ralstonia, but excluding Escherichia and Haemophilus. Individual genomes encode up to thirteen members, usually homologous to each other only in this C-terminal region. The domain's tripartite architecture consists of motif, transmembrane helix, and cluster of basic residues at the protein C-terminus, as also seen with the LPXTG recognition sequence for sortase A and the PEP-CTERM recognition sequence for exosortase. Partial Phylogenetic Profiling identifies a distinctive rhomboid-like protease subfamily almost perfectly co-distributed with this recognition sequence. This protease subfamily and its putative target domain are hereby renamed rhombosortase and GlyGly-CTERM, respectively. The protease and target are encoded by consecutive genes in most genomes with just a single target, but far apart otherwise. The signature motif of the Rhombo-CTERM domain, often SGGS, only partially resembles known cleavage sites of rhomboid protease family model substrates. Some protein families that have several members with C-terminal GlyGly-CTERM domains also have additional members with LPXTG or PEP-CTERM domains instead, suggesting there may be common themes to the post-translational processing of these proteins by three different membrane protein superfamilies.
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PMID:GlyGly-CTERM and rhombosortase: a C-terminal protein processing signal in a many-to-one pairing with a rhomboid family intramembrane serine protease. 2219 40

Rhomboid proteases are membrane-embedded proteases that cleave peptide bonds of transmembrane proteins. They play a variety of roles in cell signaling events. The rhomboid protease GlpG from Haemophilus influenzae (hiGlpG) is a canonical form of rhomboid protease having six transmembrane segments. In this unit, detailed protocols are presented for optimization of hiGlpG expression using the araBAD promotor system in the pBAD vector. The parameters for optimization include concentration of inducing agent, induction temperature, and time. Optimization of these key factors led to the development of a protocol yielding 1.6 to 2.5 mg/liter protein purified after ion metal affinity chromatography (IMAC). Further purification can include size exclusion chromatography (SEC).
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PMID:Expression and Purification of Haemophilus influenzae Rhomboid Intramembrane Protease GlpG for Structural Studies. 2469 18

Rhomboids are ubiquitous intramembrane serine proteases that cleave transmembrane substrates. Their functions include growth factor signaling, mitochondrial homeostasis, and parasite invasion. A recent study revealed that the Escherichia coli rhomboid protease EcGlpG is essential for its extraintestinal pathogenic colonization within the gut. Crystal structures of EcGlpG and the Haemophilus influenzae rhomboid protease HiGlpG have deciphered an active site that is buried within the lipid bilayer but exposed to the aqueous environment via a cavity at the periplasmic face. A lack of physiological transmembrane substrates has hampered progression for understanding their catalytic mechanism and screening inhibitor libraries. To identify a soluble substrate for use in the study of rhomboid proteases, an array of internally quenched peptides were assayed with HiGlpG, EcGlpG and PsAarA from Providencia stuartti. One substrate was identified that was cleaved by all three rhomboid proteases, with HiGlpG having the highest cleavage efficiency. Mass spectrometry analysis determined that all enzymes hydrolyze this substrate between norvaline and tryptophan. Kinetic analysis in both detergent and bicellular systems demonstrated that this substrate can be cleaved in solution and in the lipid environment. The substrate was subsequently used to screen a panel of benzoxazin-4-one inhibitors to validate its use in inhibitor discovery.
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PMID:An internally quenched peptide as a new model substrate for rhomboid intramembrane proteases. 3004 60