Positively charged amino acids placed next to a signal sequence block protein translocation more efficiently in Escherichia coli than in mammalian microsomes

1993 ◽  
Vol 239 (1-2) ◽  
pp. 251-256 ◽  
Author(s):  
Marie Johansson ◽  
IngMarie Nilsson ◽  
Gunnar von Heijne
1999 ◽  
Vol 181 (5) ◽  
pp. 1524-1529 ◽  
Author(s):  
Paolo Landini ◽  
Stephen J. W. Busby

ABSTRACT The methylated form of the Ada protein (meAda) activates transcription from the Escherichia coli ada,aidB, and alkA promoters with different mechanisms. In this study we identify amino acid substitutions in region 4 of the RNA polymerase subunit ς70 that affect Ada-activated transcription at alkA. Substitution to alanine of residues K593, K597, and R603 in ς70 region 4 results in decreased Ada-dependent binding of RNA polymerase to thealkA promoter in vitro and impairs alkAtranscription both in vivo and in vitro, suggesting that these residues define a determinant for meAda-ς70interaction. In a previous study (P. Landini, J. A. Bown, M. R. Volkert, and S. J. W. Busby, J. Biol. Chem. 273:13307–13312, 1998), we showed that a set of negatively charged amino acids in ς70 region 4 is involved inmeAda-ς70 interaction at the adaand aidB promoters. However, the alanine substitutions of positively charged residues K593, K597, and R603 do not affectmeAda-dependent transcription at ada andaidB. Unlike the ς70 amino acids involved in the interaction with meAda at the ada andaidB promoters, K593, K597, and R603 are not conserved in ςS, an alternative ς subunit of RNA polymerase mainly expressed during the stationary phase of growth. WhilemeAda is able to promote transcription by the ςS form of RNA polymerase (EςS) atada and aidB, it fails to do so atalkA. We propose that meAda can activate transcription at different promoters by contacting distinct determinants in ς70 region 4 in a manner dependent on the location of the Ada binding site.


2009 ◽  
Vol 284 (24) ◽  
pp. 16317-16324 ◽  
Author(s):  
Sandra Mueller ◽  
Gunnar Kleinau ◽  
Mariusz W. Szkudlinski ◽  
Holger Jaeschke ◽  
Gerd Krause ◽  
...  

Bovine TSH (bTSH) has a higher affinity to the human TSHR (hTSHR) and a higher signaling activity than human TSH (hTSH). The molecular reasons for these phenomena are unknown. Distinct negatively charged residues (Glu297, Glu303, and Asp382) in the hinge region of the hTSHR are known to be important for bTSH binding and signaling. To investigate the potential relevance of these positions for differences between bTSH and hTSH in the interaction to the hTSHR, we determined bTSH- and hTSH-mediated cAMP production of several substitutions at these three hinge residues. To examine specific variations of hTSH, we also investigated the superagonistic hTSH analog TR1401 (TR1401), whose sequence differs from hTSH by four additional positively charged amino acids that are also present in bTSH. To characterize possible interactions between the acidic hTSHR positions Glu297, Glu303, or Asp382 and the additional basic residues of TR1401, we investigated TR1401 binding and signaling properties. Our data reveal increased cAMP signaling of the hTSHR using TR1401 and bTSH compared with hTSH. Whereas Asp382 seems to be important for bTSH- and TR1401-mediated but not for hTSH-mediated signaling, the substitution E297K exhibits a decreased signaling for all three TSH variants. Interestingly, bTSH and TR1401 showed only a slightly different binding pattern. These observations imply that specific residues of the hinge region are mediators of the superagonistic activity of bTSH and TR1401 in contrast to hTSH. Moreover, the simultaneous localization of binding components in the glycoprotein hormone molecule and the receptor hinge region permits important reevaluation of interacting hormone receptor domains.


2001 ◽  
Vol 43 (3) ◽  
pp. 170-175 ◽  
Author(s):  
Huei-Fen Lo ◽  
Long-Liu Lin ◽  
Chien-Cheng Li ◽  
Wen-Hwei Hsu ◽  
Chen-Tien Chang

2014 ◽  
Vol 95 (9) ◽  
pp. 1919-1928 ◽  
Author(s):  
Zee Hong Goh ◽  
Nur Azmina Syakirin Mohd ◽  
Soon Guan Tan ◽  
Subha Bhassu ◽  
Wen Siang Tan

White tail disease (WTD) kills prawn larvae and causes drastic losses to the freshwater prawn (Macrobrachium rosenbergii) industry. The main causative agent of WTD is Macrobrachium rosenbergii nodavirus (MrNV). The N-terminal end of the MrNV capsid protein is very rich in positively charged amino acids and is postulated to interact with RNA molecules. N-terminal and internal deletion mutagenesis revealed that the RNA-binding region is located at positions 20–29, where 80 % of amino acids are positively charged. Substitution of all these positively charged residues with alanine abolished the RNA binding. Mutants without the RNA-binding region still assembled into virus-like particles, suggesting that this region is not a part of the capsid assembly domain. This paper is, to the best of our knowledge, the first to report the specific RNA-binding region of MrNV capsid protein.


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