Challenging a decades- old paradigm: ProB and ProA do not channel the unstable intermediate in proline synthesis after all

• 成果类型: Article
• 署名作者: Newton, Matilda S.; Azadeh, Ashley L.; Morgenthaler, Andrew B.; Copley, Shelley D.
• 署名单位: University of Colorado System; University of Colorado Boulder; University of Colorado System; University of Colorado Boulder
• 刊物名称: PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA
• ISSN/ISSBN: 0027-14366
• DOI: 10.1073/pnas.2413673121
• 发表日期: 2024-11-12
• 关键词: protein-protein interaction; 1st 2 steps; escherichia-coli; saccharomyces-cerevisiae; crystal-structure; glutamic acid; gene; biosynthesis; phosphate; kinase

摘要

The pathway for synthesis of proline in most forms of life produces a highly unstable intermediate, gamma- L- glutamyl 5- phosphate (GP). For nearly 70 y, channeling of this intermediate from the active site of glutamate 5- kinase to the active site of GP reductase has been believed to protect GP from cyclization to a dead- end product. However, the evidence presented in support of this idea is not conclusive. We show that changes in the structures of the kinase or reductase that should preclude a protein-protein interaction do not compromise proline synthesis in Escherichia coli, demonstrating that channeling does not occur. We calculate that the half- life of GP is 320 ms. Although GP is indeed unstable, it should diffuse the length of an E. coli cell in less than 3 ms. Thus, most GP produced by glutamate 5- kinase should encounter the active site of GP reductase before cyclization occurs.