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| 001 |
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| 005 |
20220104090740.0 |
| 008 |
880608s1986 xx a bm 000 0 eng d |
| 035 |
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|9 AAB0145AM
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| 035 |
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|a (OCoLC)18056463
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| 035 |
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|a (OCoLC)ocm18056463
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| 040 |
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|a TXA
|b eng
|c TXA
|d OCLCQ
|d OCLCF
|d OCLCO
|d OCLCQ
|d UMI
|d TXA
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| 049 |
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|a TXAM
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| 099 |
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|a 1986
|a Dissertation
|a R776
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| 100 |
1 |
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|a Roof, William David.
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| 245 |
1 |
0 |
|a Attenuation control of the aspartate transcarbamoylase operon in Escherichia coli.
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| 264 |
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1 |
|c 1986.
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| 300 |
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|a ix, 93 leaves :
|b illustrations ;
|c 29 cm
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| 336 |
|
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|a text
|b txt
|2 rdacontent
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| 337 |
|
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|a unmediated
|b n
|2 rdamedia
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| 338 |
|
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|a volume
|b nc
|2 rdacarrier
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| 500 |
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|a Typescript (photocopy).
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| 500 |
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|a Vita.
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| 502 |
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|b Ph. D. in Biochemistry
|c Texas A & M University
|d 1986
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| 504 |
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|a Includes bibliographical references (leaves 82-92).
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| 520 |
3 |
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|a Bacteriophage Mu dl(lac,Ap[superscript r]), a transposable element, was used to inactivate the pyrB gene by insertion. Derivatives of these pyrimidine auxotrophs were used to select the pyrB gene cloned pBR322. Three distinct structural genes were found on the larger cloned DNA fragments. The relative locations of these three genes were identified by restriction endonuclease mapping and deletion analysis. Two genes, pyrB and pyrI, encode the catalytic and regulatory polypeptides of aspartate transcarbamoylase (ATCase). A colinear map demonstrated the correlation between the restriction endonuclease sites and the known amino acid sequences for the ATCase cistrons. The pyrB and pyrI cistrons were separated by only 10-20 base pairs (bp), suggesting that these genes are organized as an ATCase operon. The DNA sequence of the early region of the operon revealed that the promoter was separated from the N-terminus of the catalytic polypeptide by approximately 160 bp. This sequence contained a Rho-independent termination sequence (an attenuator), an open reading frame capable of encoding a 44 amino acid leader polypeptide, regions of potential secondary structure, and obvious pyrimidine-rich tracts in the mRNA. This control region was cloned into pMC1403 and M13mp8 to create in-frame translational fusions between pyrB and lacZ which would express (beta)-galactosidase under pyrB control. Restriction endonucleases were used to generate deletions within the pyrB control region and these studies implicated participation by the attenuator and leader polypeptide in regulation of pyrBI expression. Nitrous acid mutagenesis of intact M13mp8::pyrB::lacZ[subscript α] generated mutations in the pyrB region that increased the expression of β-galactosidase. These mutations were single-site substitutions resulting in decreased stability of the attenuator stem. This reduction in stability resulted in increased transcription through the attenuator. It is proposed that a coupling between transcription and translation of the leader region facilitates transcription through the attenuator. Limiting pyrimidine nucleoside triphosphate levels retard transcription through pyrimidine-rich RNA tracts in the region, allowing further leader polypeptide translation and leading to an abutment of the ribosome upon the RNA polymerase. This destabilizes the RNA between them and disrupts the stem of the attenuator. Without stem formation, termination is avoided and readthrough transcription results in expression of the structural genes.
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| 650 |
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0 |
|a Escherichia coli.
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| 650 |
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0 |
|a Molecular cloning.
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| 650 |
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0 |
|a Operons.
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| 650 |
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0 |
|a Pyrimidines.
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| 650 |
|
4 |
|a Major biochemistry.
|
| 655 |
|
7 |
|a Academic theses
|2 lcgft
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| 700 |
1 |
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|a Dieckert, Julius W.,
|e degree committee member.
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| 700 |
1 |
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|a Ippen-Ihler, Karin,
|e degree committee member.
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| 700 |
1 |
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|a Pace, C. N.,
|e degree committee member.
|
| 700 |
1 |
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|a Wild, James R.,
|e degree supervisor.
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| 700 |
1 |
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|a Young, Ryland F.,
|e degree committee member.
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| 710 |
2 |
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|a Texas A & M University,
|e degree granting institution.
|
| 856 |
4 |
1 |
|u http://proxy.library.tamu.edu/login?url=http://proquest.umi.com/pqdweb?did=749104601&sid=1&Fmt=2&clientId=2945&RQT=309&VName=PQD
|z Link to ProQuest copy
|t 0
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| 856 |
4 |
1 |
|u https://hdl.handle.net/1969.1/DISSERTATIONS-23817
|z Link to OAKTrust copy
|t 0
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| 994 |
|
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|a C0
|b TXA
|
| 999 |
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|t 0
|
| 952 |
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|p noncirc
|a Texas A&M University
|b J.J. Pickle Campus
|c High Density Repository
|s HDR
|d Remote Storage
|t 0
|e 1986 Dissertation R776
|h Other scheme
|i unmediated -- volume
|m A14839616348
|
| 952 |
f |
f |
|a Texas A&M University
|b College Station
|c Electronic Resources
|s www_evans
|d Available Online
|t 0
|e 1986 Dissertation R776
|h Other scheme
|
| 998 |
f |
f |
|a 1986 Dissertation R776
|t 0
|l Available Online
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| 998 |
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|a 1986 Dissertation R776
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