烟草牻牛儿基牻牛儿基焦磷酸合成酶基因家族的全基因组鉴定

Whole Genome Identification and Analysis of Tobacco GGPP Synthase Gene Family

为了揭示烟草栊牛儿基[牛 ]牛儿基焦磷酸合成酶（Geranylgeranyl pyrophosphate synthase，GGPPS）基因家族的特征和功能，利用生物信息学方法对烟草GGPPS家族进行了全基因组查找、鉴定及相关分析。在普通烟草中共鉴定出9个成员（大亚基7个、小亚基2个），林烟草、绒毛状烟草中分别鉴定出5个成员（大亚基4个、小亚基1个）。GGPP5的开放阅读框长度为999～1119bp，编码332~372个氨基酸，蛋白质分子量为36．2～40．7kD，等电点为5．41～8．32。大亚基和小亚基基因分别含有1个和2个外显子；大亚基与小亚基均具有DD（XX）。D和CXXXC保守性基序，但存在一定的差异。在进化过程中，烟草GGPPS家族可能发生了串联重复复制和片断复制；普通烟草GGPPS家族可能发生了基因丢失，NtabGGPPS1-1和NtabGGPPS1—2较其他成员进化速率快，同时可能受到了净化选择。

In order to reveal the characteristics and functions of GGPPS （Geranylgeranyl pyrophosphate synthase） gene family in tobacco, the GGPPS family in Nicotiana tabacum （N. tabacum）, Nicotiana sylvestris （N. sylvestris） and Nicotiana tomentosiformis（N, tomentosiformis） were searched, identified and analyzed in whole genome level through in silico methods. Nine members （seven large subunits and two small subunits） in N. tabacum, and five ones （four large subunits and one small subunit） in N. sylvestris and N. tomentosiformis were identified respectively. The open reading frames of GGPPS were 999-1 119 bp in length, coded 333-372 amino acids with protein molecular weights of 36.3-40.7 kDa and pI in the range of 5.41-8.32. Small subunit genes consisted of two exons, while there was only one exon in large subunit genes. Both genes comprised DD （XX）,2D and CXXXC conservative motifs, though certain differences existed. In the course of evolution, GGPPS family in tobacco might have undergone both tandem duplication and segmental duplication, and gene loss event probably occurred in N. tabacum. In addition, NtabGGPPSI-1 and NtabGGPPS1-2 evolved faster than the other ones and might be under purifying selection.