Abstract：
:Computer analysis of the crystallographic structure of the A subunit of Escherichia coli heat-labile toxin (LT) was used to predict residues involved in NAD binding, catalysis and toxicity. Following site-directed mutagenesis, the mutants obtained could be divided into three groups. The first group contained fully assembled, non-toxic new molecules containing mutations of single amino acids such as Val-53-->Glu or Asp, Ser-63-->Lys, Val-97-->Lys, Tyr-104-->Lys or Asp, and Ser-114-->Lys or Glu. This group also included mutations in amino acids such as Arg-7, Glu-110 and Glu-112 that were already known to be important for enzymatic activity. The second group was formed by mutations that caused the collapse or prevented the assembly of the A subunit: Leu-41-->Phe, Ala-45-->Tyr or Glu, Val-53-->Tyr, Val-60-->Gly, Ser-68-->Pro, His-70-->Pro, Val-97-->Tyr and Ser-114-->Tyr. The third group contained those molecules that maintained a wild-type level of toxicity in spite of the mutations introduced: Arg-54-->Lys or Ala, Tyr-59-->Met, Ser-68-->Lys, Ala-72-->Arg, His or Asp and Arg-192-->Asn. The results provide a further understanding of the structure-function of the active site and new, non-toxic mutants that may be useful for the development of vaccines against diarrhoeal diseases.
journal_name
Mol Microbioljournal_title
Molecular microbiologyauthors
Pizza M,Domenighini M,Hol W,Giannelli V,Fontana MR,Giuliani MM,Magagnoli C,Peppoloni S,Manetti R,Rappuoli Rdoi
10.1111/j.1365-2958.1994.tb01266.xsubject
Has Abstractpub_date
1994-10-01 00:00:00pages
51-60issue
1eissn
0950-382Xissn
1365-2958journal_volume
14pub_type
杂志文章abstract：:Post-transcriptional repression of porin synthesis has emerged as a major function of Hfq-dependent, small non-coding RNAs (sRNAs). Many enterobacteria express OmpX-like porins, a family of outer membrane proteins whose physiological roles and structural properties have been studied intensively. While regulatory sRNAs...
journal_title：Molecular microbiology
pub_type： 杂志文章
doi：10.1111/j.1365-2958.2008.06189.x
更新日期：2008-05-01 00:00:00
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journal_title：Molecular microbiology
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更新日期：1998-06-01 00:00:00
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pub_type： 杂志文章,评审
doi：10.1111/j.1365-2958.1992.tb01417.x
更新日期：1992-09-01 00:00:00
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pub_type： 杂志文章
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pub_type： 杂志文章
doi：10.1111/j.1365-2958.2006.05510.x
更新日期：2007-01-01 00:00:00
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pub_type： 杂志文章
doi：10.1111/j.1365-2958.2003.03951.x
更新日期：2004-03-01 00:00:00
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pub_type： 杂志文章
doi：10.1046/j.1365-2958.2003.03396.x
更新日期：2003-03-01 00:00:00
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journal_title：Molecular microbiology
pub_type： 杂志文章
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更新日期：1989-08-01 00:00:00
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pub_type： 杂志文章
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更新日期：2002-11-01 00:00:00
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journal_title：Molecular microbiology
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更新日期：1998-07-01 00:00:00
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更新日期：1997-03-01 00:00:00
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pub_type： 杂志文章
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更新日期：1989-05-01 00:00:00
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journal_title：Molecular microbiology
pub_type： 杂志文章
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更新日期：2015-05-01 00:00:00
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journal_title：Molecular microbiology
pub_type： 杂志文章,评审
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更新日期：2003-05-01 00:00:00
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pub_type： 评论,杂志文章
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更新日期：2000-06-01 00:00:00
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pub_type： 杂志文章
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更新日期：1987-09-01 00:00:00
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journal_title：Molecular microbiology
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更新日期：2000-04-01 00:00:00
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journal_title：Molecular microbiology
pub_type： 杂志文章
doi：10.1046/j.1365-2958.1996.01533.x
更新日期：1996-12-01 00:00:00
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pub_type： 杂志文章
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更新日期：2001-01-01 00:00:00
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journal_title：Molecular microbiology
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更新日期：2002-06-01 00:00:00
