Two naturally occurring deletion mutants of 12S seed storage proteins in Arabidopsis thaliana.
Two naturally occurring Arabidopsis mutants, Cape Verde Islands and Monte (Mr-0), with aberrant 12S seed storage protein (SSP) profiles have been identified by SDS-PAGE. In both mutants, one of the 12S globulin bands is missing while a new band of lower molecular mass is present. Tandem mass spectrometry-mass spectrometry (MS/MS) analyses of the mutant peptides have revealed that both are shorter variants of 12S globulin with deletion sites detected within the alpha-subunits of 12S globulin cruciferin B (CRB) and C (CRC), respectively. Sequence analyses of the genomic DNA flanking the deletion sites have demonstrated that both deletions occurred at the genomic level. These two mutants are referred to as CRBDelta12 and CRCDelta13 with the delta sign indicating a deletion and the number indicating amino acids deleted. Alignment of these two mutant sequences with that of soybean A3B4 subunit, for which the crystal structure was determined recently, have revealed that the CRCDelta13 deletion is located in a hypervariable/disordered region, and will probably not affect the structure of the hexameric globulin. The CRBDelta12 deletion, however, is located in a binding region that is thought to be important for the hexamer formation. However, CRBDelta12 appears to accumulate normally as judged by its band intensity relative to the other SSP subunits on the protein gels. Thus it seems that the seed can, to a certain extent, tolerate some mutations in its storage proteins.
Hou
Anfu
A
Southern Crop Protection and Food Research Centre, Agriculture and Agri-Food Canada, 1391 Sandford Street, London, ON, N5V 4T3, Canada.
Liu
Kede
K
Catawatcharakul
Niramol
N
Tang
Xurong
X
Nguyen
Vi
V
Keller
Wilfred A
WA
Tsang
Edward W T
EW
Cui
Yuhai
Y
D000595:Amino Acid Sequence; D017360:Arabidopsis / Q000235:genetics*; D029681:Arabidopsis Proteins / Q000737:chemistry / Q000235:genetics*; D001483:Base Sequence; D017353:Gene Deletion; D005916:Globulins / Q000235:genetics*; D008969:Molecular Sequence Data; D021122:Protein Subunits / Q000235:genetics; D055314:Seed Storage Proteins; D012639:Seeds / Q000235:genetics*; D016415:Sequence Alignment; D017386:Sequence Homology, Amino Acid
D029681:Arabidopsis Proteins; D005916:Globulins; D021122:Protein Subunits; D055314:Seed Storage Proteins; C506890:cruciferin B, Arabidopsis; C506891:cruciferin C, Arabidopsis