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PMID:21949356

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Citation

Takeuchi, H, Fernández-Valdivia, RC, Caswell, DS, Nita-Lazar, A, Rana, NA, Garner, TP, Weldeghiorghis, TK, Macnaughtan, MA, Jafar-Nejad, H and Haltiwanger, RS (2011) Rumi functions as both a protein O-glucosyltransferase and a protein O-xylosyltransferase. Proc. Natl. Acad. Sci. U.S.A. 108:16600-5

Abstract

Mutations in rumi result in a temperature-sensitive loss of Notch signaling in Drosophila. Drosophila Rumi is a soluble, endoplasmic reticulum-retained protein with a CAP10 domain that functions as a protein O-glucosyltransferase. In human and mouse genomes, three potential Rumi homologues exist: one with a high degree of identity to Drosophila Rumi (52%), and two others with lower degrees of identity but including a CAP10 domain (KDELC1 and KDELC2). Here we show that both mouse and human Rumi, but not KDELC1 or KDELC2, catalyze transfer of glucose from UDP-glucose to an EGF repeat from human factor VII. Similarly, human Rumi, but not KDELC1 or KDELC2, rescues the Notch phenotypes in Drosophila rumi clones. During characterization of the Rumi enzymes, we noted that, in addition to protein O-glucosyltransferase activity, both mammalian and Drosophila Rumi also showed significant protein O-xylosyltransferase activity. Rumi transfers Xyl or glucose to serine 52 in the O-glucose consensus sequence ( ) of factor VII EGF repeat. Surprisingly, the second serine (S53) facilitates transfer of Xyl, but not glucose, to the EGF repeat by Rumi. EGF16 of mouse Notch2, which has a diserine motif in the consensus sequence ( ), is also modified with either O-Xyl or O-glucose glycans in cells. Mutation of the second serine (S590A) causes a loss of O-Xyl but not O-glucose at this site. Altogether, our data establish dual substrate specificity for the glycosyltransferase Rumi and provide evidence that amino acid sequences of the recipient EGF repeat significantly influence which donor substrate (UDP-glucose or UDP-Xyl) is used.

Links

PubMed PMC3189016 Online version:10.1073/pnas.1109696108

Keywords

Animals; Drosophila/genetics; Drosophila/physiology; Drosophila Proteins/genetics; Drosophila Proteins/metabolism; Factor VII/genetics; Factor VII/metabolism; Glucosyltransferases/genetics; Glucosyltransferases/metabolism; Humans; Mass Spectrometry; Mice; Mutation/genetics; Pentosyltransferases/metabolism; Signal Transduction/genetics; Signal Transduction/physiology; Substrate Specificity

Significance

Annotations

Gene product Qualifier GO Term Evidence Code with/from Aspect Extension Notes Status

MOUSE:PGLT1

enables

GO:0035251: UDP-glucosyltransferase activity

ECO:0000314: direct assay evidence used in manual assertion

F

Seeded From UniProt

complete

MOUSE:PGLT1

enables

GO:0035252: UDP-xylosyltransferase activity

ECO:0000314: direct assay evidence used in manual assertion

F

Seeded From UniProt

complete

MOUSE:PGLT1

enables

GO:0035252: UDP-xylosyltransferase activity

ECO:0000315: mutant phenotype evidence used in manual assertion

F

Seeded From UniProt

complete

HUMAN:PGLT1

acts_upstream_of_or_within

GO:0006493: protein O-linked glycosylation

ECO:0000314: direct assay evidence used in manual assertion

P

Seeded From UniProt

complete

HUMAN:PGLT1

enables

GO:0046527: glucosyltransferase activity

ECO:0000314: direct assay evidence used in manual assertion

F

Seeded From UniProt

complete

DROME:RUMI

involved_in

GO:0006493: protein O-linked glycosylation

ECO:0000314: direct assay evidence used in manual assertion

P

Seeded From UniProt

complete

DROME:RUMI

enables

GO:0140561: EGF-domain serine glucosyltransferase activity

ECO:0000314: direct assay evidence used in manual assertion

F

Seeded From UniProt

complete

DROME:RUMI

enables

GO:0140562: EGF-domain serine xylosyltransferase activity

ECO:0000314: direct assay evidence used in manual assertion

F

Seeded From UniProt

complete


See also

References

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