scholarly journals Activation of the Kexin from Schizosaccharomyces pombeRequires Internal Cleavage of Its Initially Cleaved Prosequence

1998 ◽  
Vol 18 (1) ◽  
pp. 400-408 ◽  
Author(s):  
Dale Powner ◽  
John Davey
Keyword(s):  
Cleavage Site ◽  
Secretory Pathway ◽  
Catalytic Domain ◽  
Activation Process ◽  
Processing Enzymes ◽  
Free Translation ◽  
A Cell ◽  
Internal Site ◽  
Primary Cleavage ◽  
Full Activation

ABSTRACT Members of the kexin family of processing enzymes are responsible for the cleavage of many proproteins during their transport through the secretory pathway. The enzymes themselves are made as inactive precursors, and we investigated the activation process by studying the maturation of Krp1, a kexin from the fission yeastSchizosaccharomyces pombe. Using a cell-free translation-translocation system prepared from Xenopuseggs, we found that Krp1 is made as a preproprotein that loses the presequence during translocation into the endoplasmic reticulum. The prosequence is also rapidly cleaved in a reaction that is autocatalytic and probably intramolecular and is inhibited by disruption of the P domain. Prosequence cleavage normally occurs at Arg-Tyr-Lys-Arg102↓ (primary cleavage site) but can occur at Lys-Arg82 (internal cleavage site) and/or Trp-Arg99 when the basic residues are removed from the primary site. Cleavage of the prosequence is necessary but not sufficient for activation, and Krp1 is initially unable to process substrates presented in trans. Full activation is achieved after further incubation in the extract and is coincident with the addition of O-linked sugars. O glycosylation is not, however, essential for activity, and the crucial event appears to be cleavage of the initially cleaved prosequence at the internal site. Our results are consistent with a model in which the cleaved prosequence remains noncovalently associated with the catalytic domain and acts as an autoinhibitor of the enzyme. Inhibition is then relieved by a second (internal) cleavage of the inhibitory prosequence. Further support for this model is provided by our finding that overexpression of a Krp1 prosequence lacking a cleavable internal site dramatically reduced the growth rate of otherwise wild-type S. pombecells, an effect that was not seen after overexpression of the normal, internally cleavable, prosequence or prosequences that lack the Lys-Arg102 residues.

scholarly journals A Cell-Free Translation and Proteoliposome Reconstitution System for Functional Analysis of Plant Solute Transporters

2007 ◽  
Vol 48 (12) ◽  
pp. 1815-1820 ◽  
Author(s):  
Akira Nozawa ◽  
Hideaki Nanamiya ◽  
Takuji Miyata ◽  
Nicole Linka ◽  
Yaeta Endo ◽  
...  
Keyword(s):  
Functional Analysis ◽  
Free Translation ◽  
A Cell ◽  
Solute Transporters

Regulated and constitutive secretion of distinct molecular forms of acetylcholinesterase from PC12 cells

1993 ◽  
Vol 106 (3) ◽  
pp. 731-740 ◽  
Author(s):  
E.S. Schweitzer
Keyword(s):  
Pc12 Cells ◽  
Secretory Pathway ◽  
Intracellular Localization ◽  
Synaptic Function ◽  
Molecular Forms ◽  
Secretory Proteins ◽  
Secretory Pathways ◽  
Regulated Secretion ◽  
Constitutive Secretion ◽  
A Cell

PC12 cells secrete the enzyme acetylcholinesterase (AChE) while at rest, and increase the overall rate of this secretion 2-fold upon depolarization. This behavior is different from the release of other markers by the constitutive or regulated secretory pathways in PC12 cells. Both the resting and stimulated release of AChE are unchanged after treatment with a membrane-impermeable esterase inhibitor, demonstrating that it represents true secretion and not shedding from the cell surface. The stimulation release of AChE is Ca(2+)-dependent, while the unstimulated release is not. Analysis of the molecular forms of AChE secreted by PC12 cells indicates that the release of AChE actually involves two concurrent but independent secretory processes, and that the G4 form of the enzyme is secreted constitutively, while both the G2 and G4 forms are secreted in a regulated manner, presumably from regulated secretory vesicles. Compared with other regulated secretory proteins, a much smaller fraction of cellular AChE is secreted, and the intracellular localization of this enzyme differs from that of other regulated secretory proteins. The demonstration that a cell line that exhibits regulated secretion of acetylcholine (ACh) is also capable of regulated secretion of AChE provides additional evidence for the existence of multiple regulated secretory pathways within a single cell. Moreover, there appears to be a selective packaging of different molecular forms of AChE into the regulated versus the constitutive secretory pathway. Both the specificity of sorting of AChE and the regulation of its secretion suggest that AChE may play a more dynamic role in synaptic function than has been recognized previously.

scholarly journals The 3' untranslated region of satellite tobacco necrosis virus RNA stimulates translation in vitro.

1993 ◽  
Vol 13 (6) ◽  
pp. 3340-3349 ◽  
Author(s):  
X Danthinne ◽  
J Seurinck ◽  
F Meulewaeter ◽  
M Van Montagu ◽  
M Cornelissen
Keyword(s):  
Tobacco Necrosis Virus ◽  
Translation System ◽  
Coding Region ◽  
Necrosis Virus ◽  
Untranslated Sequence ◽  
Virus Rna ◽  
Free Translation ◽  
Order Of Magnitude ◽  
A Cell

The RNA of satellite tobacco necrosis virus (STNV) is a monocistronic messenger that lacks both a 5' cap structure and a 3' poly(A) tail. We show that in a cell-free translation system derived from wheat germ, STNV RNA lacking the 600-nucleotide trailer is translated an order of magnitude less efficiently than full-size RNA. Deletion analyses positioned the translational enhancer domain (TED) within a conserved hairpin structure immediately downstream from the coat protein cistron. TED enhances translation when fused to a heterologous mRNA, but the level of enhancement depends on the nature of the 5' untranslated sequence and is maximal in combination with the STNV leader. The STNV leader and TED have two regions of complementarity. One of the complementary regions in TED resembles picornavirus box A, which is involved in cap-independent translation but which is located upstream of the coding region.

scholarly journals A murine fer testis-specific transcript (ferT) encodes a truncated Fer protein.

1990 ◽  
Vol 10 (1) ◽  
pp. 146-153 ◽  
Author(s):  
K Fischman ◽  
J C Edman ◽  
G M Shackleford ◽  
J A Turner ◽  
W J Rutter ◽  
...  
Keyword(s):  
Tyrosine Kinase ◽  
Translation System ◽  
Appearance Time ◽  
Acid Protein ◽  
Mouse Tissues ◽  
Free Translation ◽  
Alternatively Spliced ◽  
A Cell ◽  
Testis Cdna ◽  
Carboxy Terminal

A cDNA for a potential tyrosine kinase-encoding mRNA was isolated from a mouse testis cDNA library. In a survey of eight mouse tissues, a transcript of 2.4 kilobases restricted to testis tissue was found. The mRNA encodes a 453-amino-acid protein of 51,383 daltons, the smallest tyrosine kinase protein ever described. RNA synthesized from the cDNA template directs the synthesis of a 51,000-Mr protein in a cell-free translation system. The carboxy-terminal 409 amino acids are 98 and 90% identical to the carboxy halves of the rat and human Fer proteins, respectively. This suggests that the cDNA represents an alternatively spliced testis-specific fer mRNA and is therefore termed by us ferT. On the basis of the appearance time of the fer mRNA in the testis of maturing neonatal mice, we speculate on the role played by this protein in the development of this organ.

scholarly journals Secretion of Cryparin, a Fungal Hydrophobin

1999 ◽  
Vol 65 (12) ◽  
pp. 5431-5435 ◽  
Author(s):  
Patricia M. McCabe ◽  
Neal K. Van Alfen
Keyword(s):  
Cell Wall ◽  
Cell Walls ◽  
Submerged Culture ◽  
Secretory Pathway ◽  
Culture Medium ◽  
Secretory Vesicle ◽  
Cryphonectria Parasitica ◽  
Secreted Protein ◽  
Filamentous Ascomycete ◽  
A Cell

ABSTRACT Cryparin is a cell-surface-associated hydrophobin of the filamentous ascomycete Cryphonectria parasitica. This protein contains a signal peptide that directs it to the vesicle-mediated secretory pathway. We detected a glycosylated form of cryparin in a secretory vesicle fraction, but secreted forms of this protein are not glycosylated. This glycosylation occurred in the proprotein region, which is cleaved during maturation by a Kex2-like serine protease, leaving a mature form of cryparin that could be isolated from both the cell wall and culture medium. Pulse-chase labeling experiments showed that cryparin was secreted through the cell wall, without being bound, into the culture medium. The secreted protein then binds to the cell walls ofC. parasitica, where it remains. Binding of cryparin to the cell wall occurred in submerged culture, presumably because of the lectin-like properties unique to this hydrophobin. Thus, the binding of this hydrophobin to the cell wall is different from that of other hydrophobins which are reported to require a hydrophobic-hydrophilic interface for assembly.

scholarly journals Spa33, a Cell Surface-Associated Subunit of the Mxi-Spa Type III Secretory Pathway of Shigella flexneri, Regulates Ipa Protein Traffic

2001 ◽  
Vol 69 (4) ◽  
pp. 2180-2189 ◽  
Author(s):  
Raymond Schuch ◽  
Anthony T. Maurelli
Keyword(s):  
Cell Surface ◽  
Secretory Pathway ◽  
Shigella Flexneri ◽  
Mobile Element ◽  
Cell Contact ◽  
Protein Traffic ◽  
Type Iii ◽  
Transmembrane Channel ◽  
A Cell ◽  
Spa Type

ABSTRACT The Mxi-Spa type III secretion system of Shigella flexneri directs the host cell contact-induced secretion of a set of invasins, referred to as Ipas. In this study, we examined the role of Spa33 in Ipa secretion. A spa33-null mutant was both noninvasive and unable to translocate the Ipas from inner membrane to outer membrane (OM) positions of the Mxi-Spa transmembrane channel. Spa33 was found to be a Mxi-Spa substrate that is translocated to the bacterial cell surface upon the induction of Ipa secretion. This mobility may serve to drive Ipa translocation within Mxi-Spa toward OM positions. Consistent with a second distinct role in regulating Ipa traffic, the overexpression of Spa33 also blocked Ipa secretion and resulted in Ipa accumulation at the OM. Co-overexpression of Spa33 and another OM-associated element, Spa32, did not disrupt Ipa secretion, suggesting an interaction between the two proteins and an effect on the mechanism which serves to regulate Ipa release from the OM. These findings indicate that Spa33 is a mobile element within Mxi-Spa, which is required to control Ipa translocation into and out of OM positions of the secretory structure.

scholarly journals Chemical aminoacylation of tRNAs with fluorinated amino acids for in vitro protein mutagenesis

2010 ◽  
Vol 6 ◽  
Author(s):  
Shijie Ye ◽  
Allison Ann Berger ◽  
Dominique Petzold ◽  
Oliver Reimann ◽  
Benjamin Matt ◽  
...  
Keyword(s):  
Amino Acids ◽  
Translation System ◽  
Biologically Relevant ◽  
Fluorinated Amino Acids ◽  
Free Translation ◽  
Trna Species ◽  
A Cell ◽  
Protein Environment ◽  
Vitro Protein

This article describes the chemical aminoacylation of the yeast phenylalanine suppressor tRNA with a series of amino acids bearing fluorinated side chains via the hybrid dinucleotide pdCpA and ligation to the corresponding truncated tRNA species. Aminoacyl-tRNAs can be used to synthesize biologically relevant proteins which contain fluorinated amino acids at specific sites by means of a cell-free translation system. Such engineered proteins are expected to contribute to our understanding of discrete fluorines’ interaction with canonical amino acids in a native protein environment and to enable the design of fluorinated proteins with arbitrary desired properties.

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