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Title: PROTEIN QUALITY CONTROL IN BACTERIAL CELLS: INTEGRATED NETWORKS OF CHAPERONES AND ATP-DEPENDENT PROTEASES.

Abstract

It is generally accepted that the information necessary to specify the native, functional, three-dimensional structure of a protein is encoded entirely within its amino acid sequence; however, efficient reversible folding and unfolding is observed only with a subset of small single-domain proteins. Refolding experiments often lead to the formation of kinetically-trapped, misfolded species that aggregate, even in dilute solution. In the cellular environment, the barriers to efficient protein folding and maintenance of native structure are even larger due to the nature of this process. First, nascent polypeptides must fold in an extremely crowded environment where the concentration of macromolecules approaches 300-400 mg/mL and on average, each ribosome is within its own diameter of another ribosome (1-3). These conditions of severe molecular crowding, coupled with high concentrations of nascent polypeptide chains, favor nonspecific aggregation over productive folding (3). Second, folding of newly-translated polypeptides occurs in the context of their vehtorial synthesis process. Amino acids are added to a growing nascent chain at the rate of -5 residues per set, which means that for a 300 residue protein its N-terminus will be exposed to the cytosol {approx}1 min before its C-terminus and be free to begin the folding process. However, because proteinmore » folding is highly cooperative, the nascent polypeptide cannot reach its native state until a complete folding domain (50-250 residues) has emerged from the ribosome. Thus, for a single-domain protein, the final steps in folding are only completed post-translationally since {approx}40 residues of a nascent chain are sequestered within the exit channel of the ribosome and are not available for folding (4). A direct consequence of this limitation in cellular folding is that during translation incomplete domains will exist in partially-folded states that tend to expose hydrophobic residues that are prone to aggregation and/or misfolding. Thus it is not surprising that, in cells, the protein folding process is error prone and organisms have evolved ''editing'' or quality control (QC) systems to assist in the folding, maintenance and, when necessary, selective removal of damaged proteins. In fact, there is growing evidence that failure of these QC-systems contributes to a number of disease states (5-8). This chapter describes our current understanding of the nature and mechanisms of the protein quality control systems in the cytosol of bacteria. Parallel systems are exploited in the cytosol and mitochondria of eukaryotes to prevent the accumulation of misfolded proteins.« less

Authors:
;
Publication Date:
Research Org.:
Brookhaven National Lab., Upton, NY (US)
Sponsoring Org.:
USDOE Office of Energy Research (ER) (US)
OSTI Identifier:
789884
Report Number(s):
BNL-68837
TRN: US200202%%382
DOE Contract Number:
AC02-98CH10886
Resource Type:
Book
Resource Relation:
Other Information: PBD: 3 Dec 2001
Country of Publication:
United States
Language:
English
Subject:
59 BASIC BIOLOGICAL SCIENCES; AMINO ACID SEQUENCE; AMINO ACIDS; BACTERIA; DISEASES; MAINTENANCE; MITOCHONDRIA; POLYPEPTIDES; PROTEINS; QUALITY CONTROL; RESIDUES; RIBOSOMES; SYNTHESIS

Citation Formats

FLANAGAN,J.M., and BEWLEY,M.C. PROTEIN QUALITY CONTROL IN BACTERIAL CELLS: INTEGRATED NETWORKS OF CHAPERONES AND ATP-DEPENDENT PROTEASES.. United States: N. p., 2001. Web.
FLANAGAN,J.M., & BEWLEY,M.C. PROTEIN QUALITY CONTROL IN BACTERIAL CELLS: INTEGRATED NETWORKS OF CHAPERONES AND ATP-DEPENDENT PROTEASES.. United States.
FLANAGAN,J.M., and BEWLEY,M.C. 2001. "PROTEIN QUALITY CONTROL IN BACTERIAL CELLS: INTEGRATED NETWORKS OF CHAPERONES AND ATP-DEPENDENT PROTEASES.". United States. doi:. https://www.osti.gov/servlets/purl/789884.
@article{osti_789884,
title = {PROTEIN QUALITY CONTROL IN BACTERIAL CELLS: INTEGRATED NETWORKS OF CHAPERONES AND ATP-DEPENDENT PROTEASES.},
author = {FLANAGAN,J.M. and BEWLEY,M.C.},
abstractNote = {It is generally accepted that the information necessary to specify the native, functional, three-dimensional structure of a protein is encoded entirely within its amino acid sequence; however, efficient reversible folding and unfolding is observed only with a subset of small single-domain proteins. Refolding experiments often lead to the formation of kinetically-trapped, misfolded species that aggregate, even in dilute solution. In the cellular environment, the barriers to efficient protein folding and maintenance of native structure are even larger due to the nature of this process. First, nascent polypeptides must fold in an extremely crowded environment where the concentration of macromolecules approaches 300-400 mg/mL and on average, each ribosome is within its own diameter of another ribosome (1-3). These conditions of severe molecular crowding, coupled with high concentrations of nascent polypeptide chains, favor nonspecific aggregation over productive folding (3). Second, folding of newly-translated polypeptides occurs in the context of their vehtorial synthesis process. Amino acids are added to a growing nascent chain at the rate of -5 residues per set, which means that for a 300 residue protein its N-terminus will be exposed to the cytosol {approx}1 min before its C-terminus and be free to begin the folding process. However, because protein folding is highly cooperative, the nascent polypeptide cannot reach its native state until a complete folding domain (50-250 residues) has emerged from the ribosome. Thus, for a single-domain protein, the final steps in folding are only completed post-translationally since {approx}40 residues of a nascent chain are sequestered within the exit channel of the ribosome and are not available for folding (4). A direct consequence of this limitation in cellular folding is that during translation incomplete domains will exist in partially-folded states that tend to expose hydrophobic residues that are prone to aggregation and/or misfolding. Thus it is not surprising that, in cells, the protein folding process is error prone and organisms have evolved ''editing'' or quality control (QC) systems to assist in the folding, maintenance and, when necessary, selective removal of damaged proteins. In fact, there is growing evidence that failure of these QC-systems contributes to a number of disease states (5-8). This chapter describes our current understanding of the nature and mechanisms of the protein quality control systems in the cytosol of bacteria. Parallel systems are exploited in the cytosol and mitochondria of eukaryotes to prevent the accumulation of misfolded proteins.},
doi = {},
journal = {},
number = ,
volume = ,
place = {United States},
year = 2001,
month =
}

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  • It is generally accepted that the information necessary to specify the native, functional, three-dimensional structure of a protein is encoded entirely within its amino acid sequence; however, efficient reversible folding and unfolding is observed only with a subset of small single-domain proteins. Refolding experiments often lead to the formation of kinetically-trapped, misfolded species that aggregate, even in dilute solution. In the cellular environment, the barriers to efficient protein folding and maintenance of native structure are even larger due to the nature of this process. First, nascent polypeptides must fold in an extremely crowded environment where the concentration of macromolecules approachesmore » 300-400 mg/mL and on average, each ribosome is within its own diameter of another ribosome (1-3). These conditions of severe molecular crowding, coupled with high concentrations of nascent polypeptide chains, favor nonspecific aggregation over productive folding (3). Second, folding of newly-translated polypeptides occurs in the context of their vehtorial synthesis process. Amino acids are added to a growing nascent chain at the rate of {approx}5 residues per set, which means that for a 300 residue protein its N-terminus will be exposed to the cytosol {approx}1 min before its C-terminus and be free to begin the folding process. However, because protein folding is highly cooperative, the nascent polypeptide cannot reach its native state until a complete folding domain (50-250 residues) has emerged from the ribosome. Thus, for a single-domain protein, the final steps in ffolding are only completed post-translationally since {approx}40 residues of a nascent chain are sequestered within the exit channel of the ribosome and are not available for folding (4). A direct consequence of this limitation in cellular folding is that during translation incomplete domains will exist in partially-folded states that tend to expose hydrophobic residues that are prone to aggregation and/or mislfolding. Thus it is not surprising that, in cells, the protein folding process is error prone and organisms have evolved ''editing'' or quality control (QC) systems to assist in the folding, maintenance and, when necessary, selective removal of damaged proteins. In fact, there is growing evidence that failure of these QC-systems contributes to a number of disease states (5-8). This chapter describes our current understanding of the nature and mechanisms of the protein quality control systems in the cytosol of bacteria. Parallel systems are exploited in the cytosol and mitochondria of eukaryotes to prevent the accumulation of misfolded proteins.« less
  • The Federal Water Pollution Control Act Amendments were enacted by Congress in response to the severe water quality problems our nation has been experiencing. Section 208 of the Amendments establishes regional planning for water quality management as being necessary and provides strong incentives for states and municipalities to implement the Section's requirements. Section 208 planning is the subject of this thesis. An interesting and important example of the way in which water quality planning processes interact is coastal zone management. The two planning processes, 208 planning and coastal zone management, must be integrated. The problems of integrating the planning processesmore » are examined vis-a-vis five issue discussions. These are: Integration of Land and Water Planning; The Role of Local, State, and Federal Government; Coordination and Integration of Planning Processes; Sewage Disposal in the Coastal Zone; and The 208 Plan. A number of key recommendations are given for understanding and improving the planning processes. These recommendations focus on two major themes. First, the role that the states play is extremely important in the overall success of water quality management. Secondly, the review and approval process for 208 plans must be demanding and help facilitate the achievement of the goals of the law.« less
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  • Air sampling results, based on data collected in the US during 1964 and 1965, are a valuable source of information on air quality. Data are summarized that were gathered biweekly from 300 stations sampling suspended particulate matter, 30 stations sampling two gaseous pollutants, and 7 stations that continuously monitored six gaseous pollutants, suspended particulates, and soiling index. In addition to the basic data on suspended particulates and gases, data on several fractions of the particulate matter are included.
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