Reduction in Chlamydial Infectivity by Lysozyme

Kondo, LeRoy; Hanna, Lavelle; Keshishyan, H.

doi:10.3181/00379727-142-36974

Cited by 12 publications

(4 citation statements)

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“…C-type lysozyme is found in the serum (17)(18)(19), in milk (20,21), in the digestive tract (22), in the airway (23), and in all mucosal surfaces and secretions (24 -31). There is multiple evidence that lysozymes play a significant role in the control of the host microflora to prevent infection (32)(33)(34)(35)(36). Bacterial Ctype lysozyme inhibitors might thus have emerged to balance the host defense.…”

Section: Resultsmentioning

confidence: 99%

Escherichia coli ykfE ORFan Gene Encodes a Potent Inhibitor of C-type Lysozyme

Monchois¹,

Abergel²,

Sturgis³

et al. 2001

Journal of Biological Chemistry

111

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The complete nucleotide sequences of over 37 microbial and three eukaryote genomes are already publicly available, and more sequencing is in progress. Despite this accumulation of data, newly sequenced microbial genomes continue to reveal up to 50% of functionally uncharacterized "anonymous" genes. A majority of these anonymous proteins have homologues in other organisms, whereas the rest exhibit no clear similarity to any other sequence in the data bases. This set of unique, apparently species-specific, sequences are referred to as ORFans. The biochemical and structural analysis of ORFan gene products is of both evolutionary and functional interest. Here we report the cloning and expression of Escherichia coli ORFan ykfE gene and the functional characterization of the encoded protein. Under physiological conditions, the protein is a homodimer with a strong affinity for C-type lysozyme, as revealed by co-purification and co-crystallization. Activity measurements and fluorescence studies demonstrated that the YkfE gene product is a potent C-type lysozyme inhibitor (K i Ϸ 1 nM). To denote this newly assigned function, ykfE has now been registered under the new gene name Ivy (inhibitor of vertebrate lysozyme) at the E. coli genetic stock center.Despite the accumulation of sequence information from a large diversity of species and phyla, newly sequenced bacterial genomes continue to reveal a high proportion of genes of unknown function (1), including a significant subset of "ORFans" (2), i.e. putative open reading frames (ORFs) 1 without significant similarity to any previously encountered protein (or conceptual translation) sequences. Most genes found in data bases have only been predicted by computer methods and never experimentally validated. It is thus expected that some annotated ORFs, in particular among the ORFans, might not correspond to real genes. In a previous study, we verified the existence of a cognate transcript for 25 Escherichia coli ORFans with a surprising rate of success (92%) (3). Given that most ORFans appear to be transcribed, we have now initiated a systematic expression and structure determination program for the proteins encoded by these (apparently) unique genes. Because three-dimensional structures are more resilient to evolution and change than amino acid sequences, it is expected that some ORFans should exhibit structural similarity to previously described protein families, hence providing some functional hints. Alternatively, targeting ORFans for structure determination is also a suitable strategy to optimize the discovery of original protein folds, one of the goals of structural genomics.In a pilot study involving five ORFan genes, we succeeded in producing four of them in E. coli as soluble proteins, and we report here the most advanced project, ykfE. YkfE (Swiss-Prot accession number P45552; b0220 in the Blattner data base (4)) is a 474-nucleotide-long uncharacterized ORF. It is part of a single gene operon and was found to exhibit a high level of expression during the exponential...

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Section: Resultsmentioning

confidence: 99%

Escherichia coli ykfE ORFan Gene Encodes a Potent Inhibitor of C-type Lysozyme

Monchois¹,

Abergel²,

Sturgis³

et al. 2001

Journal of Biological Chemistry

111

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“…Lysozyme hydrolyzes the 1-4 glycosidic bond between N-acetylmuramic acid and N-acetylglucosamine residues in the carbohydrate backbone of peptidoglycan, which cannot be found in either chlamydial species (see "Effect of antibacterial agents on conversion of RBs to EBs" below). Lysozyme purified from hen egg white has been reported either to inactivate (227) or not to inactivate (197,512) C. trachomatis biovar trachoma. Further study of the effect of lysozymes from both PMNs and egg white is needed.…”

Section: Destruction Of Chlamydiaementioning

confidence: 99%

Interaction of chlamydiae and host cells in vitro.

Moulder¹

1991

Microbiological Reviews

513

288

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“…Egg white lysozyme has not elicited this reaction, thus indicating the presence of anti-Brucella substances in phagocyte lysosomes (29). In this connection it is noteworthy that a limited degree of chlamydial infectivity has been reported in chlamydiaeinfected tissue cultures after treatment with chicken egg white lysozyme (19).…”

Section: Discussionmentioning

confidence: 93%

Electron microscopy of the in vivo internalization of virulent Chlamydia psittaci 6BC strain

Kordová¹,

Wilt²,

Burton³

et al. 1975

Can. J. Microbiol.

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The internalization of virulent Chlamydia psittaci 6BC particles by wandering mononuclear phagocytes in the peritoneal cavity of intraperitoneally inoculated mice occurred asynchronously, i.e., fragile reticulate bodies (RB) appeared to be more readily phagocytized than the rigid elementary bodies (EB). Early damage of mononuclear phagocytes occurred after internalization of chlamydiae. This was followed by a decreased uptake of particles, and may explain the relatively long persistence (up to 6 h after inoculation) of free, extracellular, "swollen", and RB-like particles. Internalized particles within phagolysosomes showed varying degrees of disintegration. The subsequent influx of polymorphonuclear phagocytes and monocytes into the inflammed peritoneal cavity may explain the rapid disappearance of chlamydiae and their antigens from the peritoneal fluid. The alteration in ultrastructure of peritoneal cells and chlamydial parasites during the inflammatory process are discussed.

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Reduction in Chlamydial Infectivity by Lysozyme

Cited by 12 publications

References 1 publication

Escherichia coli ykfE ORFan Gene Encodes a Potent Inhibitor of C-type Lysozyme

Escherichia coli ykfE ORFan Gene Encodes a Potent Inhibitor of C-type Lysozyme

Interaction of chlamydiae and host cells in vitro.

Electron microscopy of the in vivo internalization of virulent Chlamydia psittaci 6BC strain

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