|
Holin Superfamily V
The Holin superfamily V is a superfamily of integral membrane transport proteins. It is one of the seven different holin superfamilies in total. In general, these proteins are thought to play a role in regulated cell death, although functionality varies between families and individual members. The Holin superfamily V includes the TC families: 1.E.21- The Listeria Phage A118 Holin (Hol118) Family 1.E.29- The Holin Hol44 (Hol44) Family Superfamily V includes protein families classified in the Transporter Classification Database aTC# 1.E.21anTC# 1.E.29 Both families possess members from ''Bacillota'', ''Actinomycetota'' and ''Chloroflexota''. Proteins of this superfamily all appear to have 3 transmembrane segments (TMSs) and have average sizes of 97 and 101 amino acyl residues (aas), respectively. 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 ... [...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] |
Hol118 Family
The ''Listeria'' Phage A118 Holin (Hol118) FamilyTC# 1.E.21 is a group of transporters belonging to the Holin Superfamily V. A representative list of proteins belonging to the Hol118 family can be found in thTransporter Classification Database '' Listeria monocytogenes'' bacteriophage A118 encodes a native holin, hol118, of 93 amino acyl residues (aas) exhibiting 3 putative transmembrane segments (TMSs). When cloned into lambda phage devoid of the S holin, it caused very late cell lysis, beginning 80 min. after induction. Hol118 appeared in the cytoplasmic membrane shortly after infection. A second translational start codon (AUG-3) at nucleotide position 40 in the gene gives rise to a second gene product of 83 aas lacking TMS-1 (Hol118(83)). It is produced with the full length protein, appears in the membrane, but cannot support lambda lysis and inhibits lysis by Hol118. This dominant inhibitor presumably determines the time of lysis. A homologue is found in ''L. innocua.'' The r ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Hol44 Family
The Holin Hol44 (Hol44) Family (TC# 1.E.29) is a group of transporters belonging to the Holin Superfamily V. A representative list of proteins belonging to the Hol44 family from caudovirales and Bacillota can be found in thTransporter Classification Database. One characteristic member of the Hol44 family is oenophage fOg44 (Lys44TC# 1.E.29.2.1, which secretes an endolysin that '' Oenococcus oeni'' cells are intrinsically resistant to. Full activity of Lys44 requires dissipation of the proton motive force induced by fOg44 holin during phage infection. 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 Further reading "hol44 - Hol44 - Oenococcus phage fOg44 - hol44 gene & protein" ''www.uniprot.org''. Retrieved 20 ... [...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] |
Chloroflexota
The Chloroflexota are a phylum of bacteria containing isolates with a diversity of phenotypes, including members that are aerobic thermophiles, which use oxygen and grow well in high temperatures; anoxygenic phototrophs, which use light for photosynthesis (green non-sulfur bacteria); and anaerobic halorespirers, which uses halogenated organics (such as the toxic chlorinated ethenes and polychlorinated biphenyls) as electron acceptors. The members of the phylum ''Chloroflexota'' are monoderms (that is, have one cell membrane with no outer membrane), but they stain mostly gram-negative. Many well-studied phyla of bacteria are diderms and stain gram-negative, whereas well-known monoderms that stain Gram-positive include ''Firmicutes'' (or ''Bacillota'') ( low G+C gram-positives), ''Actinomycetota'' (high-G+C gram-positives) and ''Deinococcota'' (gram-positive diderms with thick peptidoglycan). History The taxon name was created in the 2001 edition of Volume 1 of Bergey's Manual of ... [...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] |
Holins
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 calle ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
