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

The bacteriophage lysis cassette, which comprises a lysin and a holin gene, was analyzed in 18 Lactococcus lactis phages. A muramidase motif was found in the lysins of c2-like phages, while an amidase motif was observed in the lysins of 936-like phages. Both amidase and muramidase types were detected among the P335 phages. The P335 lysins were separated into three groups based on amino acid sequence identity. A class I holin was recognized in 936-like and c2-like phages, whereas P335-like phages possess class II holins. The P335 holins were further divided into four groups based on sequence identity. Only the holins of 936-like phages contained putative dual-start motifs. The unusual lysis cassette of the highly virulent P335-like phage ul36 contains a unique holin (orf74B) upstream of a lysin which is present in several other P335-like phages. Using the lambdadelta Sthf system, we demonstrated that gpORF74B induces cell lysis at the same time as lambdadelta Sthf::S105, the effector of lambda lysis. Transcriptional analysis of ul36 lysis cassette showed that first transcripts are detected 35 min after infection of L. lactis cells. The lysis clock of phage ul36 appears to be controlled by the late expression of the holin and lysin genes.
 ...
PMID:Distribution and composition of the lysis cassette of Lactococcus lactis phages and functional analysis of bacteriophage ul36 holin. 1504 67

T7 RNA polymerase selectively transcribes T7 genes during infection but is also involved in DNA replication, maturation and packaging. T7 lysozyme is an amidase that cuts a bond in the peptidoglycan layer of the cell wall, but it also binds T7 RNA polymerase and inhibits transcription, and it stimulates replication and packaging of T7 DNA. To better understand the roles of these two proteins during T7 infection, mutants of each were constructed or selected and their biochemical and physiological behavior analyzed. The amidase activity of lysozyme is needed for abrupt lysis and release of phage particles but appears to have no role in replication and packaging. The interaction between polymerase and lysozyme stimulates both replication and packaging. Polymerase mutants that gain the ability to grow normally in the absence of an interaction with lysozyme still fail to shut down late transcription and, remarkably, have become hypersensitive to inhibition when lysozyme is able to bind. These lysozyme-hypersensitive polymerases behave without lysozyme similarly to wild-type polymerase with lysozyme: both remain longer at the promoter before establishing a lysozyme-resistant elongation complex and both increase the length of pausing when elongation complexes encounter an eight-base recognition sequence involved in DNA packaging. Replication origins contain T7 promoters, but the role of T7 RNA polymerase in initiating replication is not understood well enough to more than speculate how the lysozyme-polymerase interaction stimulates replication. Maturation and packaging is apparently initiated through interaction between prohead-terminase complexes and transcription elongation complexes paused at the sequence TATCTGT(T/A), well conserved at the right-end of the concatemer junction of T7-like phages. A model that is consistent with the structure of an elongation complex and a large body of mutational and biochemical data is proposed to explain sequence-specific pausing and potential termination at the consensus recognition sequence (C/T)ATCTGT(T/A).
 ...
PMID:Multiple roles of T7 RNA polymerase and T7 lysozyme during bacteriophage T7 infection. 1522 15

Previously, the lysozyme gene of the Klebsiella phage K11 was partially sequenced in our lab. Using the sequence information the lysozyme gene of the Klebsiella phage K11 was amplified and cloned using the polymerase chain reaction of the pfu DNA polymerase. The nucleotide sequence of phage K11 lysozyme gene was determined. The open reading frame corresponds to a polypeptide with 151 amino acids and molecular weight of 16,932 Da. The deduced amino acid sequence of this polypeptide shows 74-75% homologies to the T7 and T3 phage lysozymes. Although the gene was efficiently expressed under the control of tac promoter in Escherichia coli XL1-blue cells at 37 degrees C, most of the K11 lysozyme produced was insoluble. When the temperature of cell growth was lowered, however, solubility of the K11 lysozyme was increased gradually. The insoluble protein expressed at 37 degrees C was solubilized in 5 M guanidine-HCl and refolded in the presence of oxido-shuffling agent (GSH/GSSG). Through the refolding process the recombinant lysozyme was solubilized and purified. The purified K11 lysozyme showed transcription inhibition of K11 RNA polymerase as well as amidase activity. These results showed that the lysozyme of bacteriophage K11 is a bifunctional protein that cuts a bond in the bacterial cell wall and selectively inhibits K11 phage RNA polymerase. Also, transcription inhibition ability of K11 lysozyme with T7 or SP6 phage RNA polymerase was measured. T7 RNA polymerase was less inhibited than K11 RNA polymerase by K11 lysozyme. But SP6 RNA polymerase was not nearly inhibited by K11 lysozyme.
 ...
PMID:Cloning and expression of Klebsiella phage K11 lysozyme gene. 1588 50

Natural competence for genetic transformation is the best-characterized feature of the major human pathogen Streptococcus pneumoniae. Recent studies have shown the virulence of competence-deficient mutants to be attenuated, but the nature of the connection between competence and virulence remained unknown. Here we document the release, triggered by competent cells, of virulence factors (e.g., the cytolytic toxin pneumolysin) from noncompetent cells. This phenomenon, which we name allolysis, involves a previously undescribed bacteriocin system consisting of a two-peptide bacteriocin, CibAB, and its immunity factor, CibC; the major autolysin, LytA, and lysozyme, LytC; and a proposed new amidase, CbpD. We show that CibAB are absolutely required for allolysis, whereas LytA and LytC can be supplied either by the competent cells or by the targeted cells. We propose that allolysis constitutes a competence-programmed mechanism of predation of noncompetent cells, which benefits to the competent cells and contributes to virulence by coordinating the release of virulence factors.
 ...
PMID:Competence-programmed predation of noncompetent cells in the human pathogen Streptococcus pneumoniae: genetic requirements. 1593 90

We report a structural and functional analysis of the lambda prophage Ba02 endolysin (PlyL) encoded by the Bacillus anthracis genome. We show that PlyL comprises two autonomously folded domains, an N-terminal catalytic domain and a C-terminal cell wall-binding domain. We determined the crystal structure of the catalytic domain; its three-dimensional fold is related to that of the cell wall amidase, T7 lysozyme, and contains a conserved zinc coordination site and other components of the catalytic machinery. We demonstrate that PlyL is an N-acetylmuramoyl-L-alanine amidase that cleaves the cell wall of several Bacillus species when applied exogenously. We show, unexpectedly, that the catalytic domain of PlyL cleaves more efficiently than the full-length protein, except in the case of Bacillus cereus, and using GFP-tagged cell wall-binding domain, we detected strong binding of the cell wall-binding domain to B. cereus but not to other species tested. We further show that a related endolysin (Ply21) from the B. cereus phage, TP21, shows a similar pattern of behavior. To explain these data, and the species specificity of PlyL, we propose that the C-terminal domain inhibits the activity of the catalytic domain through intramolecular interactions that are relieved upon binding of the C-terminal domain to the cell wall. Furthermore, our data show that (when applied exogenously) targeting of the enzyme to the cell wall is not a prerequisite of its lytic activity, which is inherently high. These results may have broad implications for the design of endolysins as therapeutic agents.
 ...
PMID:Structure and lytic activity of a Bacillus anthracis prophage endolysin. 1610 25

The innate immune system recognizes micro-organisms through a series of pattern recognition receptors that are highly conserved in evolution. Peptidoglycan (PGN) is a unique and essential component of the cell wall of virtually all bacteria, is not present in eukaryotes, and is an excellent target for the innate immune system. Indeed, higher eukaryotes, including mammals, have several PGN recognition molecules, including CD14, Toll-like receptor 2 (TLR2), nucleotide oligomerization domain (Nod)-containing proteins, a family of peptidoglycan recognition proteins (PGRPs), and PGN-lytic enzymes (lysozyme and amidase). These molecules induce host responses to micro-organisms, degrade PGN, or have direct antimicrobial effects.
 ...
PMID:Peptidoglycan recognition in innate immunity. 1626 4

Streptococcus pneumoniae colonizes the human upper respiratory tract, and this asymptomatic colonization is known to precede pneumococcal disease. In this report, chemically defined and semisynthetic media were used to identify the initial steps of biofilm formation by pneumococcus during growth on abiotic surfaces such as polystyrene or glass. Unencapsulated pneumococci adhered to abiotic surfaces and formed a three-dimensional structure about 25 microm deep, as observed by confocal laser scanning microscopy and low-temperature scanning electron microscopy. Choline residues of cell wall teichoic acids were found to play a fundamental role in pneumococcal biofilm development. The role in biofilm formation of choline-binding proteins, which anchor to the teichoic acids of the cell envelope, was determined using unambiguously characterized mutants. The results showed that LytA amidase, LytC lysozyme, LytB glucosaminidase, CbpA adhesin, PcpA putative adhesin, and PspA (pneumococcal surface protein A) mutants had a decreased capacity to form biofilms, whereas no such reduction was observed in Pce phosphocholinesterase or CbpD putative amidase mutants. Moreover, encapsulated, clinical pneumococcal isolates were impaired in their capacity to form biofilms. In addition, a role for extracellular DNA and proteins in the establishment of S. pneumoniae biofilms was demonstrated. Taken together, these observations provide information on conditions that favor the sessile mode of growth by S. pneumoniae. The experimental approach described here should facilitate the study of bacterial genes that are required for biofilm formation. Those results, in turn, may provide insight into strategies to prevent pneumococcal colonization of its human host.
 ...
PMID:Biofilm formation by Streptococcus pneumoniae: role of choline, extracellular DNA, and capsular polysaccharide in microbial accretion. 1693 41

Phosphocholine moieties decorating the pneumococcal surface are used as a docking station for a family of modular proteins, the so-called choline binding proteins or CBPs. Choline recognition is essential for CBPs function and may also be a determinant for their quaternary structure. There is little knowledge about modular arrangement or oligomeric structures in this family. Therefore, we have used the small angle X-ray scattering (SAXS) technique combined with analytical ultracentrifugation in order to model the three-dimensional envelope of two highly different CBPs: the phage encoded Cpl-1 lysozyme and the pneumococcal phosphorylcholine esterase Pce. Both enzymes have an N-terminal catalytic module and a C-terminal choline-binding module (CBM) that attaches them to the bacterial surface and comprises six and ten sequence repeats in Cpl-1 and Pce, respectively. SAXS experiments have shown an inherent conformational plasticity in Cpl-1 that accounts for the different relative position of these regions in the solution and crystal structures. Dimerization of Cpl-1 upon choline binding has been also visualised for the first time, and monomer-monomer interactions take place through the first CBR where a non-canonical choline binding site has now been identified. This mode of association seems to be independent of the absence or presence of the Cpl-1 catalytic module and reveals that the arrangement of the monomers differs from that previously found in the isolated CBM dimer of pneumococcal LytA amidase. In contrast, Pce displays the same modular disposition in the solution and crystal structures, and remains almost invariant upon choline binding. The present results suggest that protein dimerization and duplication of CBRs may be alternative but not equivalent ways of improving cell wall recognition by CBPs, since they provide different interaction geometries for choline residues present in (lipo)teichoic acids.
 ...
PMID:Insights into molecular plasticity of choline binding proteins (pneumococcal surface proteins) by SAXS. 1706 29

Recent studies claim a central role for Toll-like receptor (TLR) ligands in stimulating autoimmune disease by activation of antigen-presenting cells in the target organ, but it is unclear if and how TLR ligands reach target organs. Most evidence comes from rodent models, and it is uncertain whether this principle holds in primates. Here we identify which cells contain peptidoglycan (PGN) in multiple sclerosis brain and in two nonhuman primate experimental autoimmune encephalomyelitis (EAE) models with different disease courses: acute (rhesus monkey) versus chronic disease (marmoset). Because persistence of TLR ligands in the central nervous system might be consequential for disease progression, we also determined the expression of two major PGN-degrading enzymes, ie, lysozyme and N-acetylmuramyl-l-alanine amidase. Distinct phagocyte subsets, including granulocytes, macrophages, and dendritic cells, contained PGN in the brain and coexpressed the inflammatory cytokine interleukin-12. The number of phagocytes carrying PGN increased in acute and chronic EAE compared with control animals, with the highest number of PGN-containing cells in acute EAE brain. Lytic enzymes were scarcely expressed in monkey and multiple sclerosis brain, favoring PGN persistence. PGN stimulated interleukin-12p70 release by leukocytes from all three primate species. The presence of PGN in the inflamed brain may have major implications because TLR2/Nod ligation potentially promotes inflammation and disease progression.
 ...
PMID:Phagocytes containing a disease-promoting Toll-like receptor/Nod ligand are present in the brain during demyelinating disease in primates. 1707 91

The lysozymes encoded by bacteriophage T7 and K11 are both bifunctional enzymes sharing an extensive sequence homology (75%). The constructions of chimeric lysozymes were carried out by swapping the N-terminal and C-terminal domains between phage T7 and K11 lysozymes. This technique generated two chimeras, T7K11-lysozyme (N-terminal T7 domain and C-terminal K11 domain) and K11T7-lysozyme (N-terminal K11 domain and C-terminal T7 domain), which are both enzymatically active. The amidase activity of T7K11-lysozyme is comparable with the parental enzymes while K11T7-lysozyme exhibits an activity that is approximately 45% greater than the wild-type lysozymes. Moreover, these chimeric constructs have optimum pH of 7.2-7.4 similar to the parental lysozymes but exhibit greater thermal stabilities. On the other hand, the chimeras inhibit transcription comparable with the parental lysozymes depending on the source of their N-terminals. Taken together, our results indicated that domain swapping technique localizes the N-terminal region as the domain responsible for the transcription inhibition specificity of the wild type T7 and K11 lysozymes. Furthermore, we were able to develop a simple and rapid purification scheme in purifying both the wild-type and chimeric lysozymes.
 ...
PMID:Bi-functional activities of chimeric lysozymes constructed by domain swapping between bacteriophage T7 and K11 lysozymes. 1766 70


<< Previous 1 2 3 4 5 6 7 Next >>