A new allele of γ‐kafirin gene coding for a protein with high lysine content in Mexican white sorghum germplasm
2016
Chiquito‐Almanza, Elizabeth | Ochoa‐Zarzosa, Alejandra | López‐Meza, Joel E | Pecina‐Quintero, Víctor | Nuñez‐Colín, Carlos A | Anaya‐López, José L
BACKGROUND: Low protein digestibility and lysine content of white sorghum grain limit its use as a foodstuff. The increase in γ‐kafirin cross‐linking, has an important role in the reduction of protein digestibility. The objective of this study was to characterize the γ‐kafirin gene in 12 Mexican tannin‐free white sorghum genotypes and its relationship with protein digestibility and lysine content. RESULTS: Two alleles of γ‐kafirin gene were identified: alleles 1 and 7. The predicted amino acid sequence of allele 7 showed seven point mutations; six were silent, and one missense (C235G), causing the substitution P79A in the deduced amino acid sequence. In silico analysis showed that γ‐kafirin codified by allele 1 has five α‐helixes without disulfide bonds, while γ‐kafirin coding by allele 7 has four α‐helixes and three disulfide bonds. Genotypes with allele 7 had higher lysine content than those with allele 1, showing no differences in the kafirin electrophoretic profile, neither a correlation with the protein content nor the in vitro pepsin digestibility. CONCLUSIONS: Mexican tannin‐free white sorghum genotypes showed two γ‐kafirin alleles, 1 and 7. Allele 7 was associated with higher lysine content; in silico analysis showed that the substitution of P79A in this allele could modify γ‐kafirin secondary structure. © 2015 Society of Chemical Industry
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