Cysteine protease-encoding gene

In higher organisms, calpain superfamily contains 16 independent genes that modulate cellular function. Out of them, 14 are Ca2+-dependent cysteine proteases. The other two encode smaller regulatory proteins that... 

The precursor for the class III lantibiotic SapB contains a 21-amino-acid leader peptide. Two ABC-transporters RamA and RamB, consisting of 636 and 608 amino acids, respectively, are encoded by the SapB gene cluster. RamA and RamB share 31 % sequence identity however, neither contains a serine protease or cysteine protease domain. Since no other candidate proteases are present in the gene cluster, the identity of the protease that removes the leader peptide remains elusive. 

The unsaturated residues Dha and Dhb are formed by dehydration of serine and threonine residues, respectively, and the thioether linkages Lan and MeLan are generated by intramolecular Michael-type addition of cysteine thiols to the unsaturated sites (e.g., Fig. 3b). These modifications can be performed by either two separate enzymes (LanB and LanC) in class I lantibiotics or a single bifunctional enzyme (LanM) in class II lantibiotics. Typically, proteolysis of the leader sequence is performed by a dedicated protease, either a LanP serine protease (class I) or the cysteine protease domain of a LanT protein (class II). The lanB genes encode large ( 1000 residues) predominantly hydrophilic dehydratases that may be membrane associated. To date, the dehydratase activity of a LanB protein has not been reconstituted in vitro and little is known about the mechanism of catalysis of this group of enzymes. 

Using this method, several fluorescein- and biotin-tagged oligonucleotidic hybridization probes (a probe for the detection of genes encoding cysteine proteases of Fasciola hepatica, a probe for the detection of human papillomavirus (type 16)) have been synthesized and successfully used in biological studies. 

Denise H, McNeil K, Brooks DR et al (2003) Expression of multiple CPB genes encoding cysteine proteases is required for Leishmania mexicana virulence in vivo. Infect Immun 71 3190-3195... 

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