The special Sm core structure of the U7 snRNP: far-reaching significance of a small nuclear ribonucleoprotein

U7 small nuclear RNA (snRNA) is an essential component of the RNA-processing machinery which generates the 3' end of mature histone mRNA in the sea urchin. The U7 small nuclear ribonucleoprotein particle (snRNP) is classified as a member of the Sm-type U snRNP family by virtue of its recognition by both anti-trimethylguanosine and anti-Sm antibodies. We analyzed the function-structure relationship of the U7 snRNP by mutagenesis experiments. These suggested that the U7 snRNP of the sea urchin is composed of three important domains. The first domain encompasses the 5'-terminal sequences, up to about nucleotides 7, which are accessible to micrococcal nuclease, while the remainder of the RNA is highly protected and hence presumably bound by proteins. This region contains the sequence complementarities between the U7 snRNA and the histone pre-mRNA which have previously been shown to be required for 3' processing (F. Schaufele, G. M. Gilmartin, W. Bannwarth, and M. L. Birnstiel, Nature [London] 323:777-781, 1986). Nucleotides 9 to 20 constitute a second domain which includes sequences for Sm protein binding. The complementarities between the U7 snRNA sequences in this region and the terminal palindrome of the histone mRNA appear to be fortuitous and play only a secondary, if any, role in 3' processing. The third domain is composed of the terminal palindrome of U7 snRNA, the secondary structure of which must be maintained for the U7 snRNP to function, but its sequence can be drastically altered without any observable effect on snRNP assembly or 3' processing.

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Functional analysis of the sea urchin U7 small nuclear RNA.

Molecular and Cellular Biology ◽

10.1128/mcb.8.3.1076 ◽

1988 ◽

Vol 8 (3) ◽

pp. 1076-1084 ◽

Cited By ~ 19

Author(s):

G M Gilmartin ◽

F Schaufele ◽

G Schaffner ◽

M L Birnstiel

Keyword(s):

Sea Urchin ◽

Micrococcal Nuclease ◽

Small Nuclear Rna ◽

Histone Mrna ◽

Small Nuclear Ribonucleoprotein ◽

Nuclear Rna ◽

U7 Snrnp ◽

Structure Relationship ◽

Nuclear Ribonucleoprotein ◽

Sm Protein

U7 small nuclear RNA (snRNA) is an essential component of the RNA-processing machinery which generates the 3' end of mature histone mRNA in the sea urchin. The U7 small nuclear ribonucleoprotein particle (snRNP) is classified as a member of the Sm-type U snRNP family by virtue of its recognition by both anti-trimethylguanosine and anti-Sm antibodies. We analyzed the function-structure relationship of the U7 snRNP by mutagenesis experiments. These suggested that the U7 snRNP of the sea urchin is composed of three important domains. The first domain encompasses the 5'-terminal sequences, up to about nucleotides 7, which are accessible to micrococcal nuclease, while the remainder of the RNA is highly protected and hence presumably bound by proteins. This region contains the sequence complementarities between the U7 snRNA and the histone pre-mRNA which have previously been shown to be required for 3' processing (F. Schaufele, G. M. Gilmartin, W. Bannwarth, and M. L. Birnstiel, Nature [London] 323:777-781, 1986). Nucleotides 9 to 20 constitute a second domain which includes sequences for Sm protein binding. The complementarities between the U7 snRNA sequences in this region and the terminal palindrome of the histone mRNA appear to be fortuitous and play only a secondary, if any, role in 3' processing. The third domain is composed of the terminal palindrome of U7 snRNA, the secondary structure of which must be maintained for the U7 snRNP to function, but its sequence can be drastically altered without any observable effect on snRNP assembly or 3' processing.

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Core structure of the U6 small nuclear ribonucleoprotein at 1.7-Å resolution

Nature Structural & Molecular Biology ◽

10.1038/nsmb.2832 ◽

2014 ◽

Vol 21 (6) ◽

pp. 544-551 ◽

Cited By ~ 48

Author(s):

Eric J Montemayor ◽

Elizabeth C Curran ◽

Hong Hong Liao ◽

Kristie L Andrews ◽

Christine N Treba ◽

...

Keyword(s):

Core Structure ◽

Small Nuclear Ribonucleoprotein ◽

Nuclear Ribonucleoprotein

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Coilin Can Form a Complex with the U7 Small Nuclear Ribonucleoprotein

Molecular Biology of the Cell ◽

10.1091/mbc.9.10.2987 ◽

1998 ◽

Vol 9 (10) ◽

pp. 2987-3001 ◽

Cited By ~ 50

Author(s):

Michel Bellini ◽

Joseph G. Gall

Keyword(s):

Histone Gene ◽

Oocyte Nucleus ◽

Nucleic Acid Binding ◽

Transient Complex ◽

Small Nuclear Ribonucleoprotein ◽

The Matrix ◽

U7 Snrnp ◽

Spherical Structures ◽

The Many ◽

Nuclear Ribonucleoprotein

Coiled bodies (CBs) in the amphibian oocyte nucleus are spherical structures up to 10 μm or more in diameter, much larger than their somatic counterparts, which rarely exceed 1 μm. Oocyte CBs may have smaller granules attached to their surface or embedded within them, which are identical in structure and composition to the many hundreds of B-snurposomes found free in the nucleoplasm. The matrix of the CBs contains the diagnostic protein p80-coilin, which is colocalized with the U7 small nuclear ribonucleoprotein (snRNP), whereas the attached and embedded B-snurposomes contain splicing snRNPs. A few of the 50–100 CBs in the oocyte nucleus are attached to lampbrush chromosomes at the histone gene loci. By coimmunoprecipitation we show that coilin and the U7 snRNP can form a weak but specific complex in the nucleoplasm, which is dependent on the special U7 Sm-binding site. Under the same conditions coilin does not associate with the U1 and U2 snRNPs. Coilin is a nucleic acid-binding protein, as shown by its interaction with single-stranded DNA and with poly r(U) and poly r(G). We suggest that an important function of coilin is to form a transient complex with the U7 snRNP and accompany it to the CBs. In the case of CBs attached to chromosomes at the histone gene loci, the U7 snRNP is thus brought close to the actual site of histone pre-mRNA transcription.

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