Tässä haussa ei maintia CoV.
Yhteishausta "CoV ja m.-aconitaasi taas ei löytynyt yhtään mainintaa. ( Sivumennen: tulipa paljon asiaa syövästä esiin tämän entsyymin ohella)
Springer kirja CoV:sta mainitsee sivulla 109, joten kirjoitan tästä asiayhteyden sen ympäriltä.
Sitaattia kirjasta
L-Enjuanes(Ed) Coronavirus replication and reverse Genetics. SPRINGER
page 109
Cellular proteins in Coronavirus replication
Coronavirus replication involves not only the viral proteins, but also cellular proteins, which are subverted from the normal functions of the host to play roles in the viral replication system.
No coronavirus proteins in the infected cell extract could be cross-linked to the viral RNA in vitro, suggesting that viral proteins may interact with viral RNA only indirectly through cellular proteins. Several cellular proteins have been shown to bind to the regulatory elements of MHV RNA, including the 5´ and 3´ ends of the genomic RNA and the 3´ end of the negative-strand RNA and IG sites. So far, only handful of them have been identified among which hnRNP A1 and PTB are the only two proteins found to interact with regions other than the 3´ end of coronavirus genome. These proteins are likely to serve as mediators to bring the cis-regulatory regions together to form viral replication complexes. They may also help recruit and stabilize the RdRp to the initiation sites of viral RNA synthesis.
Page 110-112
HNRNP A1
, an RNA-binding protein that contains two RNA- binding domains (RBDs) and glycine -rich domain responsible for protein-protein interaction. It is predominantly nuclear protein but also shuttles between nucleus and cytoplasm. The nuclear hnRNP A1 is known to be involved in pre-mRNA splicing and transport to cellular RNAs, whereas the sytoplasmic hnRNPA1 is capable of high affinity binding to AU-rich elements and thus modulating mRNA turnover and translation. Another function of hnRNPA1 in the sytoplasm is to promote ribosome binding by a cap-mediated mechanism and to prevent spurious initiations at aberrant translation start sites. hnRNP A1 binds MHV negative-strand leader and IG sequences, which are critical elements for the discontinuous viral RNA transcription..
Page 112-114
PTB, which is also knowns as hnRNP 1, binds to the UC-rich RNA sequences typically found near 3´ end of introns. It shuttles between nucleus and cytoplasm and plays a role in the regulation of alternative splicing of pre-mRNAs and translocation of cellular and viral RNAs. PTB binds specifically to the MHV positive-strand leder RNA, which is required forMHV RNAsynthesis and regulates translation.
...
hnRNPA1 and PTB bind to the precisely complementary sites on the negative- and positive-stranded RNA, respectively, of the leader region of MHV (CoV) RNA, and also the 5´- and 3´- ends of both the positive- and negative -strand RNAs. Together they they mediate the formation of the RNP complex involving the 5´- and 3´ end fragments of MHV(CoV) RNA in vitro. The interaction between them have also been detected in a splicing complex in uninfected cells. All of thes findings support the notion that hnRNP A1 and PTB may be involved in the formation of ribonucleoprotein complex, which functions in MHV (CoV) RNA synthesis.
Most coronavirus mRNAs are capped at the 5´ end and translated by a cap-dependent mechanism. The binding of PTB to the coronavirus leader RNA , which regulates MHV RNA translation, suggests a possible role of PTB in coronavirus mRNA translation as well. Surprisingly, PTB was found to have no direct effect on the cap-dependent MHV RNA translation. it is , however, still possible that PTB may affect the IRES-mediated translation of coronavirus ORF 5b, which encodes the envelope(E) protein. The ORF 5B IRES ( internal ribosome entry site) has been shown to serve as a binding site for cellular proteins, although it is not known whether PTB is among these proteins.
Page 114-115
PABP
poly(A)-binding protein, known to interact specifically with poly(A) , which is an important , cis-acting signal for coronavirus RNA replication. RNAs with shortened poly(A) tails exhibit less in vitro PABP binding. Binding of PABP to the 3´-UTR of the Di RNA replicons correlated with the ability of the DI RNA to replicate, suggesting that the interaction between PABP and the poly(A) tail may affect coronavirus RNA replication..
The 3´UTRs of coronavirus RNA are necessary for the synthesis of negative-strand viral RNA and both genomic and subgenomic positive-strand RNA synthesis. They contain structures that are conserved among coronaviruses. It is possible that these secondary structural elements serve as binding sites for cellular proteins and functions in viral replication. Indeed, the mutations at the 3´end of the viral genomic RNA that abolishd the binding of cellular proteins also inhibited both negative-strand and positive-strand RNA synthesis, although the correlation between protein binding and RNA syntheis was not absolute (1997).
Page 115-116
Mitochondrial aconitase
The 3´- most 42 nt of the MHV genomic RNA has been shown to interact with host factors and form at least three RNA-protein complexes. Four proteins of approximately 90, 70, 58 , and 40 kDa were resolved from these complexes, and the 90- kDa protein was identified as mitochondrial aconitase (m-aconitase), which catalyzes stereospecific interconversion of citrate into isocitrate through a cis-aconitase intermediate in the Krebs cycle.
m-aconitase binds specifically to the MHV 3´ protein binding element despite the absence of a consensus RNA-binding domain. Colocalization of m-aconitase with MHV N protein was observed in virus-infected cells, suggesting interaction of m-aconitase with MHV replication complexes (2001)..
The binding properties of m-aconitase and the functional relevance of RNA binding appear to parallel those of c-aconitase.
A cytoplasmic c-aconitase, also known as iron regulatory protein 1, is a well-recognized RNA-binding protein. It is bifunctional protein, interacts with iron responsive elements located in the 5´UTR of ferritin mRNA and 3´-UTR of transferrin receptor (TfR) mRNA and to function to coordinate posttranscriptional regulation of cellular iron metabolism.
Similarly , m-aconitase can function as a posttranscriptional regulator as well- A link between cellular iron status and m-aconitase expression has also been established (1996, 1998). Increasing the intracellular level of m-aconitase of MHV -infected cells by iron supplementation resulted in increased RNA- binding activity of cell extracts and increased virus production as well as viral protein synthesis at early hours of infection. It is possible that the binding of m-aconitase to the 3´-UTR increases the stability of the viral mRNAs and hence augments the translation of viral proteins, similar to the role of IRP in regulating TfR.
Page 116-117
Other cellular protein (2005, Springer, Coronavirus replication and reverse genetics)
Accumulating evidence indicates the presence of additional cellular proteins that interact with coronavirus RNA...
The 3´-UTRs of murine and bovine coronaviruses were reported to contain bulged stem loop and pseudoknot...(1995) essential for viral replication.. potential binding sites for the proteins shown to interact with the 3´-UTRs ..
.. multiple stem-loop and hairpin-loop structures..
In the study which identified PABP, several other proteins with molecular masses of 90, 95, 40-50, and 30 kDa were also shown to interadct with the 3´-UTRs of both BCV and MHV . These cellular proteins have the potential to regulate viral RNA synthesis through their binding to the 3´ends of the coronavirus genomes; however, their identities and functions remain to be determined (2005).
Page 117-118
Proposed functions of cellular proteins ( 2005)
-because most of the viral RdRps do not appear to bind directly to the cis-acting regulatory or promoter sequences on the RNA, their ability to initiate RNA synthesis at specific sites probably depends on their interactions with the cellular proteins that bind directly to the viral RNA template
These cellular proteins may serve as a platform on which other proteins, both viral and cellular subsequently bind to form a functional replication and transcription complex(RTC)
- (Ruotsissa on useita artikkeleita ja väitöskirjoja joissa on vuoden 2005 jälkeen käsitelty koronaviruksia)
Anna Lundin( GU, Gothenburg): Candidate antivirals for treatment of respiratory syncytual virus and coronavirus infections. Identification and elucidation of mode of antiviral activity ISBN 978-91-628-8780-3
Nyt on maailamssa käynnissä 2019-nCoV uuden koronaviruksen aiheuttama purkaus , ja tästä syystä kertaan joitain perustietoja koronaviruksista tähän blogiin muistiin. Samoin kerään uusia tietoa tästä uudesta tulokkaasta. Piirrän karttakuvia vihkooni lähinnä SARS koronavirusrakenteesta käsin, sillä viruksen nonstrukturellit moninaiset proteiinit (1-169 ovat aikamoinen työkalulaatikko ja sillä on myös lisäproteiineja hankittuna. Uuden viruksen työkalukokoelmasta ja lisäproteiineista en ole vielä löytänyt eritystä spesifistä kaavakuvaa. Jos sellainen on tulollaan, se perustuu entisiin kaavoihin ja niiden suhteen tapahtuneisiin muutoksiin.Internetistä löytyy paljon hyviä
rakenneproteiinit (S, E, M, N ja apuproteiinit) tulevat sitten erikseen muista ORF open reading frame- kohdista ORF2- ja siitä eteenpäin ja osallistuvat valmiin virionin( oikeassa yläkulmassa) koostamiseen. Tapahtumat liikkuvat isäntäsolun runsaan kalvoaineksen alueella ja suojassa ja monipuoliseen kalvomateriaaliin sitten upotetaan virusproteiinit tiheästi ja virionissakin virusproteiinit kelluvat ihmissolun luovuttamassa kalvoaineksessa ja varsinkin ihmisen oman kehon alueella tuosta kalvomateriaalista ei tule mitään vierashälytystä, jos sen avulla virus fuusioituu seuraaviin soluihin, niiden kalvoista koostuneisiin järjestelmiin. S-spike proteiinin värinä on virionissa vihreä. Sillä proteiinilla virioni otata kontaktia joissain ihmissoluissa olevaan reseptoriproteiiniin ACE2 ( varsinkin keuhkojen värekarvallisissa epiteelisoluissa ja munuaistubuluksissa, muta ACE2 proteiinilla on myös liukoinen muoto, jonka TACE entsyymi voi irrottaa epiteelikalvosta, jtoen mahdollsiesti virus voi olla vireminenkin sen avulla). Tämän kuvan kyhäsin Spingerin kirjassa olevan SARS-CoV pp1a, pp1ab kaavan pohjalta. MHV viruskuva on sen vieressä kirjassa ja melkein samanlainen. ( Page 60. Overview of the domain organisation and proteolytic processing of coronavirus replicase polyprotein). Lisäksi yhdistin Sara Åkerströmin kirjassa esitetyn CoV genomiorganisaation kuvan kaikkine geeneineen, joten struktuurigeeneillekin tuli sijaa oikaan laitaan ja piirsin yhden virionin sinne ylös samoilla koodiväreillä kuin proteiineja koodaavien geenien koodit. S= vihreä , E= oranssi, M= sininen, N= karmiinin punainen .
Joten löytää uusimpia tietoja yksittäisistä virusgeenituotteista ( sekä struktuurigeeneistä, lisägeeneistä ja nons truktuurigeeneistä nsp9 ajan mtiatan kun tulee seurattua tietoja uudedsta nCoV viruksesta.
Tämä on aika palapeliasia.
Tänään vien lainakirjat, vaikka niissä on paljon asiaa, mitä ei tosiaan ole vieä ehtinyt pureskella.katson välillä netistä uusinta yksityiskohtatietoa.
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