Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:3.2.1.17 (lysozyme)
 21,489 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The insertion of a hydrophobic pentapeptide (Phe-Phe-Val-Ala-Pro) into the C-terminus in hen egg white lysozyme by genetic modification resulted in an unstable structure which caused little secretion in a yeast expression system, although this modification is useful to enhance bactericidal action to gram-negative bacteria [Ibrahim et al. (1994) J. Biol. Chem. 269, 5059-5063]. To enhance the secretion of the unstable hydrophobic pentapeptide fused lysozymes (H5-Lz), we attempted to introduce the signal sequence (Asn-X-Ser/Thr) of N-linked glycosylation into lysozyme and to suppress the quality control of the unstable mutant in the yeast expression system. The polymannosyl hydrophobic fused lysozyme (H5/G49N-Lz) having the N-glycosylation signal sequence was expressed in the medium at 3.4 times that of unglycosylated lysozyme. Further, the secretion of the unstable mutant lysozyme was done in the Saccharomyces cerevisiae disrupted calnexin gene to avoid the degradation of the unstable mutant by the quality control. Although disruption of the calnexin gene did not lead to gross effects on the levels of growth of S. cerevisiae (W303-1b), the secretion amount of H5/G49N-Lz in calnexin disrupted S. cerevisiae was 2.5 times larger than that in wild type S. cerevisiae. These results suggest that the secretion of unstable glycosylated lysozyme (H5/G49N) was suppressed by the quality control function of calnexin and that the disruption of calnexin is effective to increase the secretion of unstable glycosylated protein.
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PMID:Enhanced secretion of hydrophobic peptide fused lysozyme by the introduction of N-glycosylation signal and the disruption of calnexin gene in Saccharomyces cerevisiae. 986 32

Both glycosylated amyloidogenic lysozymes I55T/G49N and D66H/G49N were expressed in wild-type and calnexin-disrupted Saccharomyces cerevisiae. The secretion amounts of mutant I55T/G49N were almost similar in both wild-type and calnexin-disrupted S. cerevisiae. In contrast, the secretion of mutant D66H/G49N greatly increased in calnexin-disrupted S. cerevisiae, while the secretion was very low in the wild-type strain. In parallel, the induction level of the molecular chaperones BiP and PDI located in the endoplasmic reticulum (ER) was investigated when these glycosylated amyloidogenic lysozymes were expressed in wild-type and calnexin-disrupted S. cerevisiae. The mRNA concentrations of BiP and PDI were evidently increased when mutant lysozyme D66H/G49N was expressed in calnexin-disrupted S. cerevisiae, while they were not so increased when I55T/G49N mutant was expressed. This observation indicates that the conformation of mutant lysozyme D66H/G49N was less stable in the ER, thus leading to the higher-level expression of ER molecular chaperones via the unfolded protein response pathway. This suggests that glycosylated amyloidogenic lysozyme I55T/G49N may have a relatively stable conformation in the ER, thus releasing it from the quality control of calnexin compared with mutant lysozyme D66H/G49N.
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PMID:Different effects of calnexin deletion in Saccharomyces cerevisiae on the secretion of two glycosylated amyloidogenic lysozymes. 1185 82

It has been suggested that the behavior and function of Paneth cells in metaplasia are different from those found in normal intestinal mucosa. In this study, we investigated whether calnexin, a protein involved in secretory pathways, might be associated with differentiation and function of Paneth cells in normal small intestine, in complete intestinal metaplasia of the stomach, and in Paneth cell-rich adenomas. Differentiation and function of Paneth cells was monitored by Ki67, lysozyme, and morphologic features. Using a newly established monoclonal antibody, we found that calnexin is regularly synthesized by Paneth cells of normal small intestine. In these cells, the staining intensity of calnexin was inversely correlated with their content of secretory granules (lysozyme). In contrast, Paneth cells of intestinal metaplasia and Paneth cell-rich adenomas showed a reduced immunostaining of both calnexin and lysozyme. Moreover, these Paneth cells synthesized the proliferation marker Ki67, a phenomenon that was never observed in Paneth cells of normal small intestine. In vitro experiments using CaCo2 cells showed that the expression of calnexin is not directly affected by the induction of mitosis. In conclusion, calnexin probably reflects the status of Paneth cell differentiation and function. The results do not necessarily indicate that calnexin has a function in Paneth cell proliferation.
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PMID:Expression of calnexin reflects paneth cell differentiation and function. 1248 Sep 15

Secretion of proteins in Gram-negative bacteria is a high-energy-consuming process that requires translocation across two membranes and a periplasmic space composed of a mesh-like layer, the peptidoglycan. To achieve this, bacteria have evolved complex secretion systems that cross these barriers, and in many cases there are specific peptidoglycanases that degrade the peptidoglycan to allow the proper assembly of the secretion machinery. We describe here the identification and characterization of a muramidase in Brucella abortus that participates in the intracellular multiplication in professional and nonprofessional phagocytes. We demonstrated that this protein has peptidoglycanase activity, that a strain with a clean deletion of the gene displayed a defect in the early stages of the intracellular multiplication curve, and that this is dependent on the lytic activity. While neither the attachment nor the invasion of the strain was affected, we demonstrated that it had a defect in excluding the lysosomal marker LAMP-1 but not in acquiring the reticulum endoplasmic marker calnexin, indicating that the gene participates in the early stages of the intracellular trafficking but not in the establishment of the replicative niche. Analysis of the assembly status and functionality of the VirB secretion apparatus indicated that the mutant has affected the proper function of this central virulence factor.
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PMID:A lysozyme-like protein in Brucella abortus is involved in the early stages of intracellular replication. 2331 55

Cne1p is a yeast homolog of calnexin, which is a constituent of endoplasmic reticulum (ER)-associated protein quality control system in mammals. Cne1p may be involved in the degradation of misfolded lysozymes in Saccharomyces cerevisiae. To test this, c-Myc-tagged lysozymes were expressed in CNE1-deficient S. cerevisiae. The expression and secretion of an unstable lysozyme mutant G49N/D66H were enhanced and its intracellular localization was changed in the CNE1-deficient strain. Furthermore, when Cne1p was co-expressed with unstable lysozyme mutants (G49N/D66H, G49N/C76A, and K13D/G49N), its affinity to the misfolded mutant proteins was revealed by co-immunoprecipitation. The interaction with Cne1p was abrogated by the addition of tunicamycin, an inhibitor of N-glycosylation, indicating that N-linked carbohydrates might be necessary for protein binding to Cne1p. These results suggest that in yeasts, Cne1p interacts with misfolded lysozyme proteins possibly causing their retention in the ER and subsequent elimination via ER-associated degradation.
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PMID:Unstable mutant lysozymes are degraded through the interaction with calnexin homolog Cne1p in Saccharomyces cerevisiae. 2522 68