Challenging a decades-old paradigm: ProB and ProA do not channel the unstable intermediate in proline synthesis after all
Year: 2024
Type: article
Abstract: The pathway for synthesis of proline in most forms of life produces a highly unstable intermediate, γ-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.
Language: English
Subfield: Biochemistry
Domain: Life Sciences
Open Access status: hybrid
Awards: G2563694717, FPDS BASE DESCRIPTION MULTIPLE YEAR AWARD AND INCREMENTAL FUNDING FOR YEARS ONE TO FIVE. THIS PROPOSAL IS ENTITLED "RELIVING THE PAST: EXPERIMENTAL EVOLUTION OF MAJOR TRANSITIONS IN THE HISTORY OF LIFE." THIS IS AWARDED IN RESPONSE TO COOPERATIVE AGREEMENT NOTICE (CAN) NO. NNH13ZDA017C NASA ASTROBIOLOGY INSTITUTE CYCLE SEVEN (7). THE PRINCIPAL INVESTIGATOR IS DR. RAPHAEL F. ROSENZWEIG WITH UNIVERSITY OF MONTANA (UMT). PROJECT SUMMARY: TO ILLUMINATE THE LAWS THAT PRODUCE DARWIN'S "TANGLED BANK" REMAINS ONE OF BIOLOGY'S GRAND CHALLENGES ONE THAT REQUIRES UNDERSTANDING HOW DIFFERENCES AMOUNT FORMS ARE SELECTED FOR AND HOW INTERDEPENDENCE AMOUNT FORMS IS ENFORCED. IN NATURAL ENVIRONMENTS MEETING THIS CHALLENGE IS COMPLICATED BY THE FACT THAT SELECTION PRESSURES OFTEN VARY WIDELY OVER SPACE AND THROUGH TIME. LABORATORY EVOLUTION EXPERIMENTS WITH MICROBIAL POPULATION OFFER AN ATTRACTIVE ALTERNATIVE BY WHICH TO STUDY UNDER CONTROLLED CONDITIONS BOTH THE DYNAMIC INTERPLAY BETWEEN GENOTYPE AND PHENOTYPE AND THE INTERACTIONS AMONG PHENOTYPES IN SIMPLE COMMUNITIES. INDEED BECAUSE THE PRINCIPAL ACTORS IN THE FIRST 2.5 BILLION YEARS OF LIFE S DRAMA WERE EXCLUSIVELY MICROBES WE ARE OBLIGATED TO USE THESE FORMS TO UNLOCK THE SECRETS OF LIFE'S TRANSITIONS FROM SIMPLE AUTOCATALYTIC UNITS TO SELF-ORGANIZING SELF-REPLICATING ENERGY TRANSDUCTION SYSTEMS THAT RANGE IN COMPLEXITY FROM SINGLE CELLS TO ECOSYSTEMS. OUR TEAM IS RESPONDING TO NAI CAN 7 WITH A MULTIDISCIPLINARY PROPOSAL TO ADDRESS: WHAT FORCES BRING ABOUT MAJOR TRANSITIONS IN THE EVOLUTION OF BIO-COMPLEXITY? OUR PROGRAM AIMS TO MEET THE GRANT CHALLENGE OF ILLUMINATING AND INTERPRETING THE LAWS THAT PRODUCE THE "TANGLED BANK" SO THAT WE MAY BETTER UNDERSTAND AND APPRECIATE THE GRANDEUR IN THE VIEW OF LIFE....THAT WHILST THIS PLANET HAS GONE CYCLING ON ACCORDING TO THE FIXED LAW OF GRAVITY FROM SO SIMPLE A BEGINNING ENDLESS FORMS MOST BEAUTIFUL AND MOST WONDERFUL HAVE BEEN AND ARE BEING EVOLVED. THE LAWS ORIGINAL INFERRED BY DARWIN WERE THOSE THAT GIVE RISE TO NATURAL SELECTION WHICH IS A CONSEQUENCE OF NATURAL VARIATION INHERITANCE OF VARIATION AND THE DIFFERENTIAL REPRODUCTION AND SURVIVORSHIP OF VARIANTS ACCORDING TO THEIR FITNESS. 150 YEAR LATER WE NOW RECOGNIZE THE IMPORTANCE OF OTHER FACTORS IN PARTICULAR CHANGE WHETHER IN THE FORM OF GENETIC DRIFT OR HISTORICAL CONTINGENCY. OUR KNOWLEDGE OF THE MECHANISM OF INHERITANCE CONTINUES TO BE REFINED BY NEW INSIGHTS INTO WHAT CONSTITUTES A GENE HOW GENES INTERACT AND HOW MUTATION RATE ITSELF IS SUBJECT TO NATURAL SELECTION. OUR ASTROBIOLOGY PROJECT IS ORGANIZED AROUND A SET OF QUESTIONS RELATED TO MAJOR TRANSITIONS IN THE HISTORY OF LIFE WHEN INDEPENDENTLY REPLICATING ENTITIES COMBINE IN TO LARGER MORE COMPLEX WHOLES: (I) HOW DO ENZYMES AND METABOLIC NETWORKS EVOLVE? (II) HOW DID THE EUKARYOTIC CELL SPECIFICALLY THE CELL THAT CONTAINED A MITOCHONDRION COME TO BE? (III) HOW DO SYMBIOSES ARISE? (IV) HOW DOES MULTICELLULARITY EVOLVE? AND (V) HOW DO PLEIOTROPY EPISTASIS AND MUTATION RATE CONSTRAIN THE EVOLUTION OF NOVEL TRAITS? A UNIFYING THEM UNDERLYING THESE QUESTIONS IS: HOW DO COOPERATIVE VS. COMPETITIVE INTERACTIONS PLAY OUT IN DRIVING MAJOR TRANSITIONS? SEEKING THE ANSWERS TO THESE QUESTIONS FALLS SQUARELY WITHIN ASTROBIOLOGY WHICH IS THE STUDY OF THE ORIGINS EVOLUTION DISTRIBUTION AND FUTURE OF LIFE IN THE UNIVERSE AND HELPS TO ADDRESS THE FIRST OF OUR DISCIPLINE S THREE PRINCIPAL QUESTIONS: HOW DOES LIFE BEGIN AND EVOLVE?, G4828476446
OpenAlex ID: W4404182601