Herrera-Rodríguez María Begoña, Carrasco-Ballesteros Susana, Maldonado José María, Pineda Manuel, Aguilar Miguel, Pérez-Vicente Rafael
Departamento de Biología Vegetal, División de Fisiología Vegetal, Universidad de Córdoba, Avda. San Alberto Magno s/n, E-14071 Córdoba, Spain.
Departamento de Fisiología Vegetal y Ecología, Unidad de Fisiología Vegetal, Facultad de Biología, Universidad de Sevilla, Avda, Reina Mercedes 6, E-41012 Seville, Spain.
New Phytol. 2002 Jul;155(1):33-45. doi: 10.1046/j.1469-8137.2002.00437.x.
• Asparagine metabolism in sunflower (Helianthus annuus) was investigated by cDNA cloning, sequence characterization and expression analysis of three genes encoding different isoforms of asparagine synthetase (AS, EC 6.3.5.4). • The AS-coding sequences were searched for in leaves, roots and cotyledons by using a methodology based on the simultaneous amplification of different cDNAs. Three distinct AS-coding genes, HAS1, HAS1.1 and HAS2, were identified. • HAS1 and HAS1.1 are twin genes with closely related sequences that share some regulatory features. By contrast, HAS2 is a singular sequence that encodes an incomplete AS polypeptide and shows an unusual regulation. The functionality of both the complete HAS1 and the truncated HAS2 proteins was demonstrated by complementation assays. Northern analysis revealed that HAS1, HAS1.1 and HAS2 were differentially regulated dependent on the organ, the physiological status, the developmental stage and the light conditions. • Asparagine synthetase from sunflower is encoded by a small gene family whose members have achieved a significant degree of specialization to cope with the major situations requiring asparagine synthesis.
• 通过对编码天冬酰胺合成酶（AS，EC 6.3.5.4）不同同工型的三个基因进行cDNA克隆、序列表征和表达分析，研究了向日葵（Helianthus annuus）中的天冬酰胺代谢。
• 采用基于不同cDNA同时扩增的方法，在叶片、根和子叶中搜索AS编码序列。鉴定出三个不同的AS编码基因，即HAS1、HAS1.1和HAS2。
• HAS1和HAS1.1是具有密切相关序列且共享一些调控特征的孪生基因。相比之下，HAS2是一个独特的序列，编码一种不完整的AS多肽，并表现出异常的调控。通过互补试验证明了完整的HAS1蛋白和截短的HAS2蛋白的功能。Northern分析表明，HAS1、HAS1.1和HAS2的表达受器官、生理状态、发育阶段和光照条件的差异调控。
• 向日葵中的天冬酰胺合成酶由一个小基因家族编码，其成员已实现了显著程度的专业化，以应对需要合成天冬酰胺的主要情况。
