The Multispanning Membrane Protein Ste24p Catalyzes CAAX Proteolysis and NH2-terminal Processing of the Yeast a-Factor Precursor

Tam, Amy; Schmidt, W.; Michaelis, Susan

doi:10.1074/jbc.m106150200

Cited by 69 publications

(99 citation statements)

References 49 publications

(97 reference statements)

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“…6B). Ste24p belongs to a conserved family of zinc metalloproteases and proteolyzes CAAX sequences in C-terminal prenylation acceptor motifs (60). These results raise the possibility of a previously unappreciated role for Ste24p in the translocation machinery or in the translocation of a subset of secreted proteins.…”

Section: Figurementioning

confidence: 64%

J Domain Co-chaperone Specificity Defines the Role of BiP during Protein Translocation

Vembar

Jonikas

Hendershot

et al. 2010

Journal of Biological Chemistry

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Hsp70 chaperones can potentially interact with one of several J domain-containing Hsp40 co-chaperones to regulate distinct cellular processes. However, features within Hsp70s that determine Hsp40 specificity are undefined. To investigate this question, we introduced mutations into the ER-lumenal Hsp70, BiP/ Kar2p, and found that an R217A substitution in the J domaininteracting surface of BiP compromised the physical and functional interaction with Sec63p, an Hsp40 required for ER translocation. In contrast, interaction with Jem1p, an Hsp40 required for ER-associated degradation, was unaffected. Moreover, yeast expressing R217A BiP exhibited defects in translocation but not in ER-associated degradation. Finally, the genetic interactions of the R217A BiP mutant were found to correlate with those of known translocation mutants. Together, our results indicate that residues within the Hsp70 J domain-interacting surface help confer Hsp40 specificity, in turn influencing distinct chaperone-mediated cellular activities.Most newly synthesized proteins require the assistance of molecular chaperones to fold into their native conformations. In addition, chaperones facilitate the assembly of macromolecular structures. To perform these functions, chaperones noncovalently bind to surface-exposed hydrophobic patches, thus preventing protein aggregation and, in some cases, providing a secure folding environment (1, 2). One family of chaperones, heat shock proteins of 70 kDa (Hsp70s), 3 forms a major component of the cellular folding and stress response machinery (3, 4). Hsp70s are quite abundant and can be found in nearly every cellular compartment in eukaryotes and in most prokaryotes. Not surprisingly, they catalyze a multitude of functions, including protein folding, transport, and degradation.Hsp70s contain a conserved N-terminal ATPase domain, followed by a less conserved substrate binding domain (SBD) and a variable C-terminal "lid." The lid is flexible and helps confine the substrate within the SBD. The Hsp70 ATP hydrolytic cycle correlates with substrate binding and release, such that the ADP-bound state of Hsp70s has a higher affinity for substrates than the ATP-bound state. Because the ATPase activity of Hsp70s is weak, Hsp40 co-chaperones are needed to accelerate ATP hydrolysis and promote maximal chaperone activity (5-7). Select Hsp40 family members can also deliver substrates to Hsp70s. The interaction between Hsp70s and Hsp40s is mediated by the Hsp40 J domain, an ϳ70-amino acid motif that forms a four-helix bundle. Notably, an invariant HPD motif between helices 2 and 3 of the J domain plays a critical role in facilitating Hsp70-Hsp40 interaction.In recent years, it has become clear that Hsp40s are more diverse than Hsp70s (8). For example, Escherichia coli encode three Hsp70s and six Hsp40s, whereas the budding yeast Saccharomyces cerevisiae expresses 14 Hsp70s and 22 Hsp40s. The diversity increases in higher eukaryotes, with humans expressing 20 Hsp70s and Ͼ50 Hsp40s. Moreover, a single Hsp70 can interact with m...

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Section: Figurementioning

confidence: 64%

J Domain Co-chaperone Specificity Defines the Role of BiP during Protein Translocation

Vembar

Jonikas

Hendershot

et al. 2010

Journal of Biological Chemistry

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“…The gene encoding Zmpste24 was discovered in our laboratory in a screen for sterile mutants in yeast (hence the designation STE24), and we established biochemically that it carries out critical proteolytic processing steps in the biogenesis of the mating pheromone a-factor (11)(12)(13). In mammals, the importance of Zmpste24 function is only now becoming appreciated through mouse knockout studies (8,9) and the discovery of several human diseases that result from a lack of Zmpste24 cleavage of prelamin A.…”

Section: Lack Of Zmpste24 Processing Of Prelamin a In Human Disease Andmentioning

confidence: 99%

“…1 A, step 4) (8)(9)(10). Zmpste24 is a protease in the endoplasmic reticulum membrane and was first identified in budding yeast, where it catalyzes aaXing (in which it is functionally redundant with Rce1) and an internal cleavage in the a-factor mating pheromone, as also occurs in prelamin A (11)(12)(13). Lamin B, like lamin A, undergoes CaaX modifications; however, notably, lamin B is not internally cleaved.…”

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confidence: 99%

Inhibiting farnesylation reverses the nuclear morphology defect in a HeLa cell model for Hutchinson-Gilford progeria syndrome

Mallampalli

Huyer

Bendale

et al. 2005

Proc. Natl. Acad. Sci. U.S.A.

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Hutchinson-Gilford progeria syndrome (HGPS) is a devastating premature aging disease resulting from a mutation in the LMNA gene, which encodes nuclear lamins A and C. Lamin A is synthesized as a precursor (prelamin A) with a C-terminal CaaX motif that undergoes farnesylation, endoproteolytic cleavage, and carboxylmethylation. Prelamin A is subsequently internally cleaved by the zinc metalloprotease Ste24 (Zmpste24) protease, which removes the 15 C-terminal amino acids, including the CaaX modifications, to yield mature lamin A. HGPS results from a dominant mutant form of prelamin A (progerin) that has an internal deletion of 50 aa near the C terminus that includes the Zmpste24 cleavage site and blocks removal of the CaaX-modified C terminus. Fibroblasts from HGPS patients have aberrant nuclei with irregular shapes, which we hypothesize result from the abnormal persistence of the farnesyl and͞or carboxylmethyl CaaX modifications on progerin. If this hypothesis is correct, inhibition of CaaX modification by mutation or pharmacological treatment should alleviate the nuclear morphology defect. Consistent with our hypothesis, we find that expression in HeLa cells of GFP-progerin or an uncleavable form of prelamin A with a Zmpste24 cleavage site mutation induces the formation of abnormal nuclei similar to those in HGPS fibroblasts. Strikingly, inhibition of farnesylation pharmacologically with the farnesyl transferase inhibitor rac-R115777 or mutationally by alteration of the CaaX motif dramatically reverses the abnormal nuclear morphology. These results suggest that farnesyl transferase inhibitors represent a possible therapeutic option for individuals with HGPS and͞or other laminopathies due to Zmpste24 processing defects.aging ͉ posttranslational processing ͉ laminopathy ͉ Ste24p ͉ Zarnestra

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“…Because membrane spans are not commonly a feature of proteases, purification was important in providing proof that Ste24p is a bona fide CaaX protease 25 . Ste24p contains a canonical zinc metal-loprotease motif, and the purified enzyme is zinc dependent.…”

Section: Enzymatic Processing Of Prenylated Proteinsmentioning

confidence: 99%

Therapeutic intervention based on protein prenylation and associated modifications

et al. 2006

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In eukaryotic cells, a specific set of proteins are modified by C-terminal attachment of 15-carbon farnesyl groups or 20-carbon geranylgeranyl groups that function both as anchors for fixing proteins to membranes and as molecular handles for facilitating binding of these lipidated proteins to other proteins. Additional modification of these prenylated proteins includes C-terminal proteolysis and methylation, and attachment of a 16-carbon palmitoyl group; these modifications augment membrane anchoring and alter the dynamics of movement of proteins between different cellular membrane compartments. The enzymes in the protein prenylation pathway have been isolated and characterized. Blocking protein prenylation is proving to be therapeutically useful for the treatment of certain cancers, infection by protozoan parasites and the rare genetic disease Hutchinson-Gilford progeria syndrome.Isoprenoids are lipids made of five-carbon blocks, and they constitute one of the main classes of natural products. A subset of isoprenoids called prenyl groups are found on a variety of biological substances, including proteins. Prenylated proteins and peptides are found in most (if not all) eukaryotes. They arise from the post-translational attachment of 15-carbon farnesyl or 20-carbon geranylgeranyl groups to the C-terminal segment of proteins. Protein prenyl groups not only are hydrophobic elements that bind proteins to membranes, but, at least in some cases, they also function as molecular handles that bind to hydrophobic grooves on the surface of soluble protein factors; these factors then remove the prenylated protein from the membrane in a regulated manner. NIH Public Access Author ManuscriptNat Chem Biol. Author manuscript; available in PMC 2010 June 28. Published in final edited form as:Nat Chem Biol. 2006 October ; 2(10): 518-528. doi:10.1038/nchembio818. NIH-PA Author ManuscriptNIH-PA Author Manuscript NIH-PA Author ManuscriptProtein prenylation has been vigorously studied over the past ~15 years because it is found on several signaling proteins (including heterotrimeric G proteins) that connect cell surface receptors to intracellular effectors, and also on Ras proteins, one of the most common oncoproteins found in human tumors. Ras proteins serve as molecular switches at cellular membranes to control propagation of growth signals from cell surface receptors to nuclear transcription factors. Because Ras mutations are important in many human cancers, there has been extensive focus on Ras prenylation. Discovery of protein prenyl groups and structural varietiesThe first reports of prenylated proteins and peptides described the secreted pheromone peptides from jelly fungi 1,2 , whose structure resembles that of the well-known a-factor mating pheromone from baker's yeast (Saccharomyces cerevisiae), which contains a cysteine methylester farnesylated at the C terminus 3 . In the 1980s, studies on the timing of cholesterol biosynthesis with respect to the cell cycle in human cells led to the discovery that a compound deriv...

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The Multispanning Membrane Protein Ste24p Catalyzes CAAX Proteolysis and NH2-terminal Processing of the Yeast a-Factor Precursor

Cited by 69 publications

References 49 publications

J Domain Co-chaperone Specificity Defines the Role of BiP during Protein Translocation

J Domain Co-chaperone Specificity Defines the Role of BiP during Protein Translocation

Inhibiting farnesylation reverses the nuclear morphology defect in a HeLa cell model for Hutchinson-Gilford progeria syndrome

Therapeutic intervention based on protein prenylation and associated modifications

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