Circular minidefensins and posttranslational generation of molecular diversity.
We purified two new minidefensins (RTD-2 and RTD-3) from the bone marrow of rhesus monkeys. Both were circular octadecapeptides that contained three intramolecular disulfide bonds and were homologous to RTD-1, a circular (theta) defensin previously described by Tang et al. (Science, 286, 498-502, 1999). However, whereas the 18 residues of RTD-1 represent spliced nonapeptide fragments derived from two different demidefensin precursors, RTD-2 and -3 comprise tandem nonapeptide repeats derived from only one of the RTD-1 precursors. Thus, circular minidefensins are products of a novel posttranslational system that generates effector molecule diversity without commensurate genome expansion. A system wherein two demidefensin genes can produce three circular minidefensins might allow n such genes to produce (n/2)(n+1) peptides.
Leonova
L
L
Department of Medicine, UCLA School of Medicine, UCLA, Los Angeles, California 90095-1690, USA.
Kokryakov
V N
VN
Aleshina
G
G
Hong
T
T
Nguyen
T
T
Zhao
C
C
Waring
A J
AJ
Lehrer
R I
RI
D000595:Amino Acid Sequence; D000818:Animals; D001853:Bone Marrow / Q000378:metabolism; D003001:Cloning, Molecular; D023082:Defensins / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism*; D004220:Disulfides / Q000737:chemistry; D014644:Genetic Variation; D006801:Humans; D008253:Macaca mulatta / Q000235:genetics / Q000378:metabolism*; D008969:Molecular Sequence Data; D010084:Oxidation-Reduction; D010456:Peptides, Cyclic / Q000138:chemical synthesis; D016133:Polymerase Chain Reaction; D011499:Protein Processing, Post-Translational; D012333:RNA, Messenger / Q000235:genetics; D017386:Sequence Homology, Amino Acid
D023082:Defensins; D004220:Disulfides; D010456:Peptides, Cyclic; D012333:RNA, Messenger; C435493:RTD-2 protein, Macaca mulatta; C435494:RTD-3 protein, Macaca mulatta