摘要
The 'central dogma 'of molecular biology indicated that the direction of the genetic information flow is from DNA - RNA - protein. However, up to now, the central dogma has not obtained a sufficient theoretical support from cybernetics and information theory. In addition, some special cases in biology, such as, although the scrapie prion is irreversibly inactivated by alkali, five procedures with more specificity for modifying nucleic acids failed to cause inactivation and when a resting cell is activated by some factors and division occurs, protein synthesis has begun before DNA synthesis etc., are also very difficult to explain clearly by the central dogma. A broad outline of a mechanism for reverse translation can easily be 'designed', based on the normal translation process, and this serves both to prove that there is no fundamental theoretical reason for the central dogma, and to illustrate why the redundancy of genetic code is not a problem.This paper, based on some previous research work of authors, from the view of cybernetics, information theory and theoretical biology, explored the possibility of protein as a genetic information carrier, the probable pairing ways between ammo acids-codons, and the direction of genetic information flows etc., at theory, by comparing and analyzing theoretically the characteristics of information carriers existing in DNA and protein. The authors inferred that perhaps protein may join the informational transferring as a genetic information carrier; the direction of genetic information flows, besides the way described by the central dogma, seem also to have another type, that is, genetic information flowing from protein - DNA (RNA) - protein, which also includes the genetic information flow in the central dogma. Undoubtedly, the research on problems about the position and roles of protein during the genetic information transferring will have an important effect on the investigation and development of molecular biology, molecular genetics and gene engineering.
分子生物学的“中心法则”表明:遗传信息的方向是从DNA→RNA→蛋白质。然而,截止目前为止,中心法则仍未从控制论和信息论获得足够的理论支持。此外,生物学中的一些特殊情况,例如,虽然用碱可使羊骚痒病基因不可逆地失活,但用对核酸具专一修饰作用的5种方法却都未能使其失活;另外,当间期细胞被某些因素激活并造成分裂时,在DNA合成之前蛋白质的合成就已经开始等,也都很难用中心法则来解释清楚。基于正常的翻译过程,也能容易地“设计”一个逆翻译机制的大概轮廓,并且这种机制既可以证明为什么中心法则没有理论基础,同时又可以说明遗传密码的简并性。 本文根据作者先前的一些研究结果,从控制论、信息论和理论生物学的角度,通过对DNA和蛋白质所存在的遗传信息载体的特征进行理论比较和分析的基础上,就蛋白质作为遗传信息载体的可能性、氨基酸-密码子间可能的配对方式以及遗传信息流的方向等问题进行了探讨。作者推测,蛋白质也许可作为遗传信息的载体参加信息的传递;遗传信息的传递除了中心法则所描述的途径外,似乎还有另外的一条途径,即遗传信息沿蛋白质→DNA(RNA)→蛋白质的方向流动,这里也包括了中心法则所描述的遗传信息流。毫无疑问,有关蛋白质在遗传信息传递过程中的位置与作用的研究,将会对分子生物学,?
基金
国家自然科学基金
中国科学院昆明动物研究所细胞与分子进化开放研究实验室资助项目
