| 词条 | Retron |
| 释义 |
| Name = Retron msr RNA | image = RF00170.jpg | width = 200px | caption = Predicted secondary structure and sequence conservation of msr | Symbol = msr | AltSymbols = | Rfam = RF00170 | miRBase = | miRBase_family = | RNA_type = Gene | Tax_domain = Bacteria | GO = | SO = {{SO|0000233}} | CAS_number = | EntrezGene = | HGNCid = | OMIM = | PDB = | RefSeq = | Chromosome = | Arm = | Band = | LocusSupplementaryData = }} A retron is a distinct DNA sequence found in the genome of many bacteria species that codes for reverse transcriptase and a unique single-stranded DNA/RNA hybrid called multicopy single-stranded DNA (msDNA). Retron msr RNA is the non-coding RNA produced by retron elements and is the immediate precursor to the synthesis of msDNA. The retron msr RNA folds into a characteristic secondary structure that contains a conserved guanosine residue at the end of a stem loop. Synthesis of DNA by the retron-encoded reverse transcriptase (RT) results in a DNA/RNA chimera which is composed of small single-stranded DNA linked to small single-stranded RNA. The RNA strand is joined to the 5' end of the DNA chain via a 2'-5' phosphodiester linkage that occurs from the 2' position of the conserved internal guanosine residue. For many years after their discovery in animal viruses, reverse transcriptase was believed to be absent from prokaryotes. Currently, however, RT-encoding elements, i.e. retroelements, have been found in a wide variety of different bacteria. Retrons were the first family of retroelement discovered in bacteria; the other two families of known bacterial retroelements are group II introns and diversity-generating retroelements (DGRs).[2] Group II introns are the best characterized bacterial retroelement and the only type known to exhibit autonomous mobility; they consist of an RT encoded within a catalytic, self-splicing RNA structure. Group II intron mobility is mediated by a ribonucleoprotein comprising an intron lariat bound to two intron-coded proteins. The second family of bacterial retroelement, DGRs, are not mobile, but function to diversify DNA sequences.[3] For example, DGRs mediate the switch between pathogenic and free-living phases of Bordetella.[4] Since retrons are not mobile, their appearance in diverse bacterial species is not a "selfish DNA" phenomenon. Rather, retrons must confer some selective advantage to the host organism. What this advantage may be is unknown. Except for producing msDNA, no clear phenotype has been associated with them. Despite considerable investigation, very little is known about the function of msDNA, the mobility of retron elements, or their effect on the host cell.[5][6] References1. ^{{cite journal |vauthors=Lampson BC, Inouye M, Inouye S |title=Retrons, msDNA, and the bacterial genome |journal=Cytogenet Genome Res |volume=110 |issue=1–4 |pages=491–9 |year=2005 |url=http://gcat.davidson.edu/sybr-u/Lampson_2005.pdf |pmid=16093702 |doi=10.1159/000084982}} 2. ^{{cite journal |vauthors=Simon DM, Zimmerly S |title=A diversity of uncharacterized reverse transcriptases in bacteria |journal=Nucleic Acids Res. |volume=36 |issue=22 |pages=7219–29 |year=2008 |url=http://nar.oxfordjournals.org/content/36/22/7219.short |doi=10.1093/nar/gkn867}} 3. ^{{cite journal |vauthors=Medhekar B, Mille JF |title=Diversity-Generating Retroelements |journal=Current Opinion in Microbiology |volume=10 |issue=4 |pages=388–395 |year=2007 |doi=10.1016/j.mib.2007.06.004 |pmc=2703298 |pmid=17703991}} 4. ^{{cite journal |vauthors=Liu M, Gingery M, Doulatov SR, Liu Y, Hodes A, Baker S, Davis P, Simmonds M, Churcher C, Mungall K, Quail MA, Preston A, Harvill ET, Maskell DJ, Eiserling FA, Parkhill J, Miller JF |title=Genomic and Genetic Analysis of Bordetella Bacteriophages Encoding Reverse Transcriptase-Mediated Tropism-Switching Cassettes|journal=J. Bacteriol. |volume=186 |issue=5 |pages=1503–17 |year=2004 |doi=10.1128/JB.186.5.1503-1517.2004 |pmc=344406 |pmid=14973019}} 5. ^{{cite journal | last = Ahmed | first = AM |author2=Shimamoto T | year = 2003 | title = msDNA-St85, a multicopy single-stranded DNA isolated from Salmonella enterica serovar Typhimurium LT2 with the genomic analysis of its retron | journal = FEMS Microbiol Lett | volume = 224 | pages = 291–297 | pmid = 12892895 | doi = 10.1016/S0378-1097(03)00450-6 | issue = 2}} 6. ^{{cite journal | last = Lampson | first = BC |author2=Xu C |author3=Rice SA |author4=Inouye S | year = 2002 | title = A partial copy of msDNA from a new retron element is likely a retrotransposed DNA found in the myxobacterium Nannocystis exedens | journal = Gene | volume = 299 | pages = 251–261 | pmid = 12459273 | doi = 10.1016/S0378-1119(02)00977-0 | issue = 1–2}} External links
1 : Non-coding RNA |
| 随便看 |
|
开放百科全书收录14589846条英语、德语、日语等多语种百科知识，基本涵盖了大多数领域的百科知识，是一部内容自由、开放的电子版国际百科全书。