Homologues of metazoan snRNAs

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Homologues of metazoan U1, U2, U4, U5, and U6 snRNAs, which form the catalytic core of the spliceosome, have been identified in the hemiascomycetous yeasts on the basis of sequence conservation and shared structural elements with their metazoan counterparts [Guthrie & Patterson, 1988; Roiha et al., 1989; Bon et al. 2003].

U1, U2 and U5 snRNAs are highly polymorphic in size and general organisation in the hemiascomycetous yeasts compared to their S. pombe and mammals counterparts, suggesting that a part of the splicing machinery has diverged in the hemiascomycetous yeasts [Kaufer & Potashkin, 2000; Bon et al., 2003].

By contrast, U4 and U6 snRNAs homologues are relatively well conserved in length and sequence, probably reflecting evolutionary constraints imposed by the interaction between these molecules.

Note that the functional features like the intron base-pairing site and the Sm site (PuAT4-6G-Pu), involved respectively in the contact between the snRNAs and the splice sites and the Sm protein, are evolutionary conserved between organisms.

  Accession to snRNA sequences  
snRNA: U1 U2 U4 U5 U6
Yeast species
S. cerevisiae M17205 M14625 M17238 M16510 X12565
S. uvarum - - - - -
S. exiguus - - - - -
S. servazzii - - - - -
Z. rouxii(b) AR0AA014A08CP1(n) - - AR0AA020B08CP1 (r) -
S. kluyveri (b) - AU0AA010F08T1 (n) AU0AA006A07T1 (n) - -
K. thermotolerans (b) AY0AA003C07DP1 (n) - - - AY0AA012H12TP1 (r)
K. lactis - - - BA0AB004C05LP1 (r) BA0AB015B07LP1 (n)
K. marxianus - - - AZ0AA010E03T1 (r) -
C. tropicalis(b) - - - - -
C. albicans © - Contig6_2470 (r) Contig6_2246 (r) Contig6_2516 (n) Contig6_2500 (n)
D. hansenii (b) - - BC0AA001A12T2 (n) -  
P. sorbitophila (b) - - - - AX0AA026E03CP1 (n)
P. angusta (b) - - - XBB0AA002D05T1 (n) BB0AA028D08DP1 (r)
Y. lipolytica (b) - - AW0AA001A07D1 (r) - -
Legend (a) GenBank accession number
(b) Génolevures accession number
(c) The Stanford's C. albicans sequence assembly 6
(n) Sequence orientation: normal
(r) Sequence orientation : reverse and complement>

Last modified: Tue Feb 10 11:15:04 CET 2004