|
Holin Superfamily IV
The Holin superfamily IV is a superfamily of integral membrane transport proteins. It is one of the seven different holin superfamilies in total. The Holin superfamily IV includes the TC families: 1.E.10- The ''Bacillus subtilis'' φ29 Holin (φ29 Holin) Family 1.E.16- The Cph1 Holin (Cph1 Holin) Family 1.E.19- The ''Clostridium difficile'' TcdE Holin (TcdE Holin) Family 1.E.40- The Mycobacterial 4 TMS Phage Holin (MP4 Holin) Family Superfamily IV includes four TC families, which includes members from ''Bacillota'', ''Actinomycetota'' and ''Fusobacteriota''. Their average sizes are (in amino acyl residues (aas)): TC# 1.E.10 - 138 ± 6 aas TC# 1.E.16 - 149 ± 15 aas TC# 1.E.19 - 141 ± 12 aas TC# 1.E.40 - 173 ± 149 aas Thus, there is very little size variation among family members, except for family 40, which has members larger than the other proteins in this superfamily. All members of families 10 and 19 and many members of family 16 appear to have 3 transmembrane segment ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Protein Superfamily
A protein superfamily is the largest grouping (clade) of proteins for which common ancestry can be inferred (see homology (biology), homology). Usually this common ancestry is inferred from structural alignment and mechanistic similarity, even if no sequence similarity is evident. Sequence homology can then be deduced even if not apparent (due to low sequence similarity). Superfamilies typically contain several protein families which show sequence similarity within each family. The term ''protein clan'' is commonly used for protease and glycosyl hydrolases superfamilies based on the MEROPS and CAZy classification systems. Identification Superfamilies of proteins are identified using a number of methods. Closely related members can be identified by different methods to those needed to group the most evolutionarily divergent members. Sequence similarity Historically, the similarity of different amino acid sequences has been the most common method of inferring Sequence homology, h ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Membrane Transport Protein
A membrane transport protein (or simply transporter) is a membrane protein involved in the movement of ions, small molecules, and macromolecules, such as another protein, across a biological membrane. Transport proteins are integral transmembrane proteins; that is they exist permanently within and span the membrane across which they transport substances. The proteins may assist in the movement of substances by facilitated diffusion or active transport. The two main types of proteins involved in such transport are broadly categorized as either ''channels'' or ''carriers''. The solute carriers and atypical SLCs are secondary active or facilitative transporters in humans. Collectively membrane transporters and channels are known as the transportome. Transportomes govern cellular influx and efflux of not only ions and nutrients but drugs as well. Difference between channels and carriers A carrier is not open simultaneously to both the extracellular and intracellular environments. ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Holin
Holins are a diverse group of small proteins produced by dsDNA bacteriophages in order to trigger and control the degradation of the host's cell wall at the end of the lytic cycle. Holins form pores in the host's cell membrane, allowing lysins to reach and degrade peptidoglycan, a component of bacterial cell walls. Holins have been shown to regulate the timing of lysis with great precision. Over 50 unrelated gene families encode holins, making them the most diverse group of proteins with common function. Together with lysins, holins are being studied for their potential use as antibacterial agents. While canonical holins act by forming large pores, pinholins such as the S protein of lambdoid phage 21 act by forming heptameric channels that depolarize the bacterial membrane. They are associated with SAR endolysins, which remain inactive in the periplasm prior to the depolarization of the membrane. Viruses that infect eukaryotic cells may use similar channel-forming proteins called ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Phi29 Holin Family
The ''Bacillus subtilis'' φ29 Holin (φ29 Holin) Family (TC# 1.E.10) is a group of transporters belonging to the Holin Superfamily IV. A representative list of members belonging to the φ29 holin family can be found in the Transporter Classification Database. The phage φ29 gene 14 encodes the protein GP14 (TC# 1.E.10.1.1) which is required for phage φ29-promoted host cell lysis. When expressed in ''E. coli'', it leads to cell death without lysis. When expressed together with phage φ29 lysozyme or an unrelated murein-degrading enzyme, cell lysis is also observed. Thus, GP14 is a nonspecific holin in the cytoplasmic membrane of ''B. subtilis.'' It is identical to the phage PZA lysis protein and nearly identical to the phage B103 lysis protein. It is 34% identical to the phage GA-1 holin. See also * Holin * Lysin Lysins, also known as endolysins or murein hydrolases, are hydrolytic enzymes produced by bacteriophages in order to cleave the host's cell wall during the fina ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cph1 Holin Family
The Cph1 Holin FamilyTC# 1.E.16 is also called the CDD Holin 4 superfamily, but belongs to the Holin Superfamily IV as classified in the Transporter Classification Database (TCDB). A representative list of members belonging to the Cph1 family can be found iTCDB See also * Holin * Lysin Lysins, also known as endolysins or murein hydrolases, are hydrolytic enzymes produced by bacteriophages in order to cleave the host's cell wall during the final stage of the lytic cycle. Lysins are highly evolved enzymes that are able to target ... * Transporter Classification Database References Holins Protein families {{Membrane-protein-stub ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
TcdE Holin Family
The ''Clostridium difficile'' TcdE Holin (TcdE Holin) FamilyTC# 1.E.19 is a group of transporters belonging to the Holin Superfamily IV. A representative list of its members can be found in thTransporter Classification Database Toxigenic strains of ''C. difficile'' produce two large toxins (TcdA and TcdB) encoded within a pathogenicity locus. ''tcdE,'' encoded between ''tcdA'' and ''tcdB,'' encodes a 166 amino acyl (aa) protein which causes death to ''E. coli'' when expressed, and the structure of TcdE resembles holins. TcdE acts on the bacterial membrane. Since TcdA and TcdB lack signal peptides, they may be released via TcdE either prior to or subsequent to cell lysis. Other Clostridial species bear homologues of TcdE. The transport reaction believed to be catalyzed by TcdE is:Toxin (in) → Toxin (out) See also * Holin * Lysin * Clostridium difficile toxin A * Clostridium difficile toxin B * Transporter Classification Database Further reading * Dingle, Kate E.; Elliott ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
MP4 Holin Family
The Mycobacterial 4 TMS Phage Holin (MP4 Holin) FamilyTC# 1.E.40 is a group of transporters belonging to Holin superfamily IV. A representative list of members belonging to the MP4 holin family can be found in the Transporter Classification Database. A member of the Mycobacterial 4 transmembrane segment (TMS) Phage Holin family was first identified by Catalao ''et al.'' This small family includes several 4 TMS homologues, from mycobacterial phage and cyanobacteria. See also * Holin * Lysin Lysins, also known as endolysins or murein hydrolases, are hydrolytic enzymes produced by bacteriophages in order to cleave the host's cell wall during the final stage of the lytic cycle. Lysins are highly evolved enzymes that are able to target ... * Transporter Classification Database References Holins Protein families {{Membrane-protein-stub ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Bacillota
The Bacillota (synonym Firmicutes) are a phylum of bacteria, most of which have gram-positive cell wall structure. The renaming of phyla such as Firmicutes in 2021 remains controversial among microbiologists, many of whom continue to use the earlier names of long standing in the literature. The name "Firmicutes" was derived from the Latin words for "tough skin," referring to the thick cell wall typical of bacteria in this phylum. Scientists once classified the Firmicutes to include all gram-positive bacteria, but have recently defined them to be of a core group of related forms called the low- G+C group, in contrast to the Actinomycetota. They have round cells, called cocci (singular coccus), or rod-like forms (bacillus). A few Firmicutes, such as ''Megasphaera'', ''Pectinatus'', ''Selenomonas'' and ''Zymophilus'', have a porous pseudo-outer membrane that causes them to stain gram-negative. Many Bacillota (Firmicutes) produce endospores, which are resistant to desiccation and can ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Actinomycetota
The ''Actinomycetota'' (or ''Actinobacteria'') are a phylum of all gram-positive bacteria. They can be terrestrial or aquatic. They are of great economic importance to humans because agriculture and forests depend on their contributions to soil systems. In soil they help to decompose the organic matter of dead organisms so the molecules can be taken up anew by plants. While this role is also played by fungi, ''Actinomycetota'' are much smaller and likely do not occupy the same ecological niche. In this role the colonies often grow extensive mycelia, like a fungus would, and the name of an important order of the phylum, '' Actinomycetales'' (the actinomycetes), reflects that they were long believed to be fungi. Some soil actinomycetota (such as ''Frankia'') live symbiotically with the plants whose roots pervade the soil, fixing nitrogen for the plants in exchange for access to some of the plant's saccharides. Other species, such as many members of the genus '' Mycobacterium'', ar ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Fusobacteriota
Fusobacteriota are obligately anaerobic non-sporeforming Gram-negative bacilli. Since the first reports in the late nineteenth century, various names have been applied to these organisms, sometimes with the same name being applied to different species. More recently, not only have there been changes to the nomenclature, but also attempts to differentiate between species which are believed to be either pathogenic or commensal or both. Because of their asaccharolytic nature, and a general paucity of positive results in routine biochemical tests, laboratory identification of the Fusobacteriota has been difficult. However, the application of novel molecular biological techniques to taxonomy has established a number of new species, together with the subspeciation of ''Fusobacterium necrophorum'' and ''F. nucleatum'', and provided new methods for identification. The involvement of Fusobacteriota in a wide spectrum of human infections causing tissue necrosis and septicaemia has long bee ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Lysin
Lysins, also known as endolysins or murein hydrolases, are hydrolytic enzymes produced by bacteriophages in order to cleave the host's cell wall during the final stage of the lytic cycle. Lysins are highly evolved enzymes that are able to target one of the five bonds in peptidoglycan (murein), the main component of bacterial cell walls, which allows the release of progeny virions from the lysed cell. Cell-wall-containing Archaea are also lysed by specialized pseudomurein-cleaving lysins, while most archaeal viruses employ alternative mechanisms. Similarly, not all bacteriophages synthesize lysins: some small single-stranded DNA and RNA phages produce membrane proteins that activate the host's autolytic mechanisms such as autolysins. Lysins are being used as antibacterial agents due to their high effectiveness and specificity in comparison with antibiotics, which are susceptible to bacterial resistance. Structure Double-stranded DNA phage lysins tend to lie within the 25 to 40 ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
