A 41 amino acid motif in importin-alpha confers binding to importin-beta and hence transit into the nucleus.

A subset of bacterial periplasmic enzymes are transported from the cytoplasm by the twin-arginine transport apparatus. Such proteins contain distinctive N-terminal signal peptides containing a conserved SRRXFLK ‘twin-arginine’ amino acid motif and often bind complex cofactors before the transport event. It is important that assembly of complex cofactor-containing, and often multi-subunit, enzymes is complete before export. Studies of the unrelated [NiFe] hydrogenase, DMSO reductase and trimethylamine N-oxide reductase systems from Escherichia coli have enabled us to define a chaperone-mediated ‘proofreading’ mechanism involved in co-ordinating assembly and export of twin-arginine transport-dependent enzymes.

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Charged Amino Acids Conserved in the Aromatic Acid/H+ Symporter Family of Permeases Are Required for 4-Hydroxybenzoate Transport by PcaK from Pseudomonas putida

Journal of Bacteriology ◽

10.1128/jb.184.5.1444-1448.2002 ◽

2002 ◽

Vol 184 (5) ◽

pp. 1444-1448 ◽

Cited By ~ 26

Author(s):

Jayna L. Ditty ◽

Caroline S. Harwood

Keyword(s):

Amino Acids ◽

Amino Acid ◽

Pseudomonas Putida ◽

Essential Amino Acid ◽

Major Facilitator Superfamily ◽

Aromatic Acid ◽

Transmembrane Segment ◽

Amino Acid Motif ◽

Charged Amino Acids ◽

Major Facilitator

ABSTRACT Charged amino acids in the predicted transmembrane portion of PcaK, a permease from Pseudomonas putida that transports 4-hydroxybenzoate (4-HBA), were required for 4-HBA transport, and they were also required for P. putida to have a chemotactic response to 4-HBA. An essential amino acid motif (DGXD) containing aspartate residues is located in the first transmembrane segment of PcaK and is conserved in the aromatic acid/H+ symporter family of the major facilitator superfamily of transporters.

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Importin alpha can migrate into the nucleus in an importin beta- and Ran-independent manner

The EMBO Journal ◽

10.1093/emboj/cdf569 ◽

2002 ◽

Vol 21 (21) ◽

pp. 5833-5842 ◽

Cited By ~ 79

Author(s):

Y. Miyamoto

Keyword(s):

Independent Manner ◽

Importin Beta ◽

Importin Alpha

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Diversity of Substitutions within or Adjacent to Conserved Amino Acid Motifs of Penicillin-Binding Protein 2X in Cephalosporin-Resistant Streptococcus pneumoniaeIsolates

Antimicrobial Agents and Chemotherapy ◽

10.1128/aac.43.5.1252 ◽

1999 ◽

Vol 43 (5) ◽

pp. 1252-1255 ◽

Cited By ~ 60

Author(s):

Yasuko Asahi ◽

Yasuo Takeuchi ◽

Kimiko Ubukata

Keyword(s):

Streptococcus Pneumoniae ◽

Amino Acid ◽

Three Dimensional ◽

Crystallographic Structure ◽

Amino Acid Substitutions ◽

Penicillin Binding Protein ◽

Amino Acid Motif ◽

Dna Fragment ◽

High Level ◽

Level Resistance

ABSTRACT The sequence of an approximately 1.1-kb DNA fragment of thepbp2x gene, which encodes the transpeptidase domain, was determined for 35 clinical isolates of Streptococcus pneumoniae for which the cefotaxime (CTX) MICs varied. Strains with substitutions within a conserved amino acid motif changing STMK to SAFK and a Leu-to-Val change just before the KSG motif were highly resistant to CTX (MIC, ≧2 μg/ml). Strains with substitutions adjacent to SSN or KSG motifs had low-level resistance. The amino acid substitutions were plotted on the three-dimensional crystallographic structure of the transpeptidase domain of PBP2X. Transformants containing pbp2x from strains with high-level CTX resistance increased the CTX MIC from 0.016 μg/ml to 0.5 to 1.0 μg/ml.

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