Protein Family Models

SprB is a large, repeat-rich protein (over 6000 amino acids) exported to the cell surface by a type IX secretion system (T9SS) and involved in gliding motility. Homologous repeats are found in other bacterial proteins of various lengths, most of them also T9SS-dependent for export.

Date:

2024-10-16

Bacterial periplasmic or secreted endonuclease I (EC:3.1.21.1) E. coli endonuclease I (EndoI) is a sequence independent endonuclease located in the periplasm. It is inhibited by different RNA species. It is thought to normally generate double strand breaks in DNA, except in the presence of high salt concentrations and RNA, when it generates single strand breaks in DNA. Its biological role is unknown [1]. Other family members are known to be extracellular [2]. This family also includes a non-specific, Mg2+ activated ribonuclease precursor (Swiss:Q03091) [3]. [1]. 7867949. The periplasmic endonuclease I of Escherichia coli has amino-acid sequence homology to the extracellular DNases of Vibrio cholerae and Aeromonas hydrophila. Jekel M, Wackernagel W;. Gene 1995;154:55-59. [2]. 3036665. Extracellular proteins of Vibrio cholerae: molecular cloning, nucleotide sequence and characterization of the deoxyribonuclease (DNase) together with its periplasmic localization in Escherichia coli K-12. Focareta T, Manning PA;. Gene 1987;53:31-40. [3]. 1396690. Gene cloning and characterization of a novel extracellular ribonuclease of Bacillus subtilis. Nakamura A, Koide Y, Miyazaki H, Kitamura A, Masaki H, Beppu T, Uozumi T;. Eur J Biochem 1992;209:121-127. (from Pfam)

Date:

2024-10-16

This large family of proteins includes magnesium dependent endonucleases and a large number of phosphatases involved in intracellular signalling [1]. This family includes: AP endonuclease proteins EC:4.2.99.18 e.g Swiss:P27695, DNase I proteins EC:3.1.21.1 e.g. Swiss:P24855, Synaptojanin an inositol-1,4,5-trisphosphate phosphatase EC:3.1.3.56 Swiss:O43426, Sphingomyelinase EC:3.1.4.12 Swiss:P11889 and Nocturnin Swiss:O35710. [1]. 10838565. Functionally unrelated signalling proteins contain a fold similar to Mg2+-dependent endonucleases. Dlakic M;. Trends Biochem Sci 2000;25:272-273. [2]. 7885481. Structure and function of the multifunctional DNA-repair enzyme exonuclease III. Mol CD, Kuo CF, Thayer MM, Cunningham RP, Tainer JA;. Nature 1995;374:381-386. [3]. 1748997. DNase I-induced DNA conformation. 2 A structure of a DNase I-octamer complex. Lahm A, Suck D;. J Mol Biol 1991;222:645-667. (from Pfam)

Date:

2024-10-16

Date:

2024-08-14

Type IX secretions systems (T9SS) occur in the Bacteroidetes, such as Cytophaga hutchinsonii and Flavobacterium johnsoniae, and are required for the type of gliding motility seen in that lineage, although they are not limited processing target proteins from that system. The C-terminal domain described by TIGR04183, recognized as sorting signal by T9SS, is now known as type A, and is quite distinct from type B (see TIGR04131). Most targets of T9SS are cleaved by a transpeptidase and then attached to a component of the outer membrane, but a few are released in soluble form.

Date:

2023-07-13