Biology:Hamiltonella defensa
| Hamiltonella defensa | |
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| Species: | H. defensa
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| Hamiltonella defensa Moran et al., 2005
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Hamiltonella defensa (H. defensa) is a species of bacteria. It is maternally or sexually transmitted and lives as an endosymbiont of whiteflies and aphids,[1] meaning that it lives within a host, protecting its host from attack. It does this through bypassing the host's immune responses by protecting its host against parasitoid wasps.[2] However, H. defensa is only defensive if infected by a virus. H. defensa shows a relationship with Photorhabdus species, together with Regiella insecticola. Together with other endosymbionts, it provides aphids protection against parasitoids.[2] It is known to habitate Bemisia tabaci.[3]
H. defensa is a member of the family Enterobacteriaceae.[4] It can be found both extracellularly and intracellulary in H. defensa itself, and also the bacteriocytes.[4] It is a gram-negative bacteria and has been found to have six distinct secretion systems that mediate the export of protein through the inner and outer membranes.[4][5] In general, "Candidatus Hamiltonella defensa's" functions are relatively unknown,[3] and the H. defensa's discovery was not specified by a particular person.
H. defensa's draft genome sequence was first discovered in the B. tabaci complex of the "Candidatus Hamiltonella defensa".[3] This is only found in two invasive cryptic species: Mediterranean and Middle East-Asia.[3]
The H. defensa is significantly smaller (at 1.84-Mpb) than its bacteria relatives; Yersinia and Serratia species. It is also dependent on the essential amino acids produced by Buchnera.[2] It is autotrophic for eight out of the ten essential amino acids that Buchnera produces.[6] Although dependent, the H. defensa genome preserves more genes and pathways for cell structures and processes, than that of obligate symbionts. It also has several abundances: toxin homologs, encoding type-3 secretion systems, and putative pathogenicity loci.[2] Additionally, H. defensa holds mobile DNA, like phage-derived genes, plasmids, and insertion-sequence elements, that feature H. defensa's dynamicness, and also show the role horizontal gene transfer has on shaping it.[2] The H. defensa genome holds a 2,110,331-bp circular chromosome and a 59,034-bp conjugative plasmid. The chromosome carries a canonical origin of replication.[6] It has notably more cell structure, DNA replication, recombination, and repair of genes than obligate endosymbionts, despite its limited biosynthetic abilities.[6] The proteins present in H. defensa vary in length significantly. They have a double cycled nonapeptide sequence involved in binding calcium.[6]
Special properties
H. defensa has two types of type-3 secretion systems (T3SS).[6] These translocation systems are typically used by pathogens to occupy host cells and elude immune responses.[6] They are also necessary for the perseverance of certain symbiosis.[6]
There have been recent studies done attempting to find ways to manipulate H.defensa's "self-fighting" qualities, and create a cure for certain illnesses.[vague][citation needed]
References
- ↑ "Evolutionary relationships of three new species of Enterobacteriaceae living as symbionts of aphids and other insects". Applied and Environmental Microbiology 71 (6): 3302–10. June 2005. doi:10.1128/AEM.71.6.3302-3310.2005. PMID 15933033.
- ↑ 2.0 2.1 2.2 2.3 2.4 "Hamiltonella defensa, genome evolution of protective bacterial endosymbiont from pathogenic ancestors". Proceedings of the National Academy of Sciences of the United States of America 106 (22): 9063–8. June 2009. doi:10.1073/pnas.0900194106. PMID 19451630. Bibcode: 2009PNAS..106.9063D.
- ↑ 3.0 3.1 3.2 3.3 "Draft genome sequence of "Candidatus Hamiltonella defensa," an endosymbiont of the whitefly Bemisia tabaci". Journal of Bacteriology 194 (13): 3558. July 2012. doi:10.1128/JB.00069-12. PMID 22689243.
- ↑ 4.0 4.1 4.2 "Immunity and symbiosis". Molecular Microbiology 73 (5): 751–9. September 2009. doi:10.1111/j.1365-2958.2009.06820.x. PMID 19656293.
- ↑ Team, BioModels.net. "BioModels Database". http://www.ebi.ac.uk/biomodels-main/BMID000000000892.
- ↑ 6.0 6.1 6.2 6.3 6.4 6.5 6.6 "Hamiltonella defensa, genome evolution of protective bacterial endosymbiont from pathogenic ancestors". Proc Natl Acad Sci USA 106 (22): 9063–9068. June 2009. doi:10.1073/pnas.0900194106. PMID 19451630. Bibcode: 2009PNAS..106.9063D.
Wikidata ☰ Q2936284 entry
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