PROSITE documentation PDOC00459
Ribonuclease T2 family histidine active sites


The fungal ribonucleases T2 from Aspergillus oryzae, M from Aspergillus saitoi and Rh from Rhizopeus niveus are structurally and functionally related 30 Kd glycoproteins [1] that cleave the 3'-5' internucleotide linkage of RNA via a nucleotide 2',3'-cyclic phosphate intermediates (EC

A number of other RNAses have been found to be evolutionary related to these fungal enzymes:

  • Self-incompatibility [2] in flowering plants is often controlled by a single gene (S-gene) that has several alleles. This gene prevents fertilization by self-pollen or by pollen bearing either of the two S- alleles expressed in the style. The self-incompatibility glycoprotein from several higher plants of the solanaceae family has been shown [2,3] to be a ribonuclease.
  • Phosphate-starvation induced RNAses LE and LX from tomato [4]. These two enzymes are probably involved in a phosphate-starvation rescue system.
  • Escherichia coli periplasmic RNAse I (EC (gene rna) [5].
  • Aeromonas hydrophila periplasmic RNAse.
  • Haemophilus influenzae hypothetical protein HI0526.

Two histidines residues have been shown [6,7] to be involved in the catalytic mechanism of RNase T2 and Rh. These residues and the region around them are highly conserved in all the sequence described above. We have developed two signature patterns, one for each of the two active-site histidines. The second pattern also contains a cysteine which is known to be involved in a disulfide bond.

Last update:

April 2006 / Pattern revised.


Technical section

PROSITE methods (with tools and information) covered by this documentation:

RNASE_T2_1, PS00530; Ribonuclease T2 family histidine active site 1  (PATTERN)

RNASE_T2_2, PS00531; Ribonuclease T2 family histidine active site 2  (PATTERN)


1AuthorsWatanabe H. Naitoh A. Suyama Y. Inokuchi N. Shimada H. Koyama T. Ohgi K. Irie M.
TitlePrimary structure of a base non-specific and adenylic acid preferential ribonuclease from Aspergillus saitoi.
SourceJ. Biochem. 108:303-310(1990).
PubMed ID2229029

2AuthorsHaring V. Gray J.E. McClure B.A. Anderson M.A. Clarke A.E.
TitleSelf-incompatibility: a self-recognition system in plants.
SourceScience 250:937-941(1990).
PubMed ID2237440

3AuthorsMcClure B.A. Haring V. Ebert P.R. Anderson M.A. Simpson R.J. Sakiyama F. Clarke A.E.
TitleStyle self-incompatibility gene products of Nicotiana alata are ribonucleases.
SourceNature 342:955-957(1989).
PubMed ID2594090

4AuthorsLoeffler A. Glund K. Irie M.
SourceEur. J. Biochem. 214:627-633(1993).

5AuthorsMeador J. III Kennell D.
TitleCloning and sequencing the gene encoding Escherichia coli ribonuclease I: exact physical mapping using the genome library.
SourceGene 95:1-7(1990).
PubMed ID2253883

6AuthorsKawata Y. Sakiyama F. Hayashi F. Kyogoku Y.
TitleIdentification of two essential histidine residues of ribonuclease T2 from Aspergillus oryzae.
SourceEur. J. Biochem. 187:255-262(1990).
PubMed ID2298207

7AuthorsKurihara H. Mitsui Y. Ohgi K. Irie M. Mizuno H. Nakamura K.T.
TitleCrystal and molecular structure of RNase Rh, a new class of microbial ribonuclease from Rhizopus niveus.
SourceFEBS Lett. 306:189-192(1992).
PubMed ID1633875

8AuthorsBairoch A.
SourceUnpublished observations (1993).

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