Gudula Grammer

Publications (5)53.3 Total impact

• Article: Foamy virus envelope protein is a substrate for signal peptide peptidase like-3 (SPPL3).

  Matthias Voss, Akio Fukumori, Peer-Hendrik Kuhn, Ulrike Künzel, Bärbel Klier, Gudula Grammer, Martina Haug-Kröper, Elisabeth Kremmer, Stefan Lichtenthaler, Harald Steiner, Bernd Schröder, Christian Haass, Regina Fluhrer
  [show abstract] [hide abstract]
  ABSTRACT: Signal peptide peptidase (SPP), its homologues the SPP-like proteases SPPL2a/b/c, and SPPL3 as well as presenilin, the catalytic subunit of the γ-secretase complex, are intramembrane-cleaving aspartyl proteases of the GxGD type. In this study we identified the 18 kDa leader peptide (LP18) of the foamy virus envelope protein (FVenv) as a new substrate for intramembrane proteolysis by human SPPL3 and SPPL2a/b. In contrast to SPPL2a/b and γ-secretase, which require substrates with an ectodomain shorter than 60 amino acids for efficient intramembrane proteolysis, SPPL3 cleaves mutant FVenv, lacking the pro-protein convertase cleavage site necessary for the preceding shedding. Moreover, the cleavage product of FVenv generated by SPPL3 serves as a new substrate for consecutive intramembrane cleavage by SPPL2a/b. Thus human SPPL3 is the first GxGD type aspartyl protease shown to be capable of acting like a sheddase, similar to members of the rhomboid family, which belong to the class of intramembrane cleaving serine proteases.
  Journal of Biological Chemistry 11/2012; · 4.77 Impact Factor
• Article: The α-helical content of the transmembrane domain of the British dementia protein-2 (Bri2) determines its processing by signal peptide peptidase-like 2b (SPPL2b).

  Regina Fluhrer, Lucas Martin, Bärbel Klier, Martina Haug-Kröper, Gudula Grammer, Brigitte Nuscher, Christian Haass
  [show abstract] [hide abstract]
  ABSTRACT: Regulated intramembrane proteolysis is a widely accepted concept describing the processing of various transmembrane proteins via ectodomain shedding followed by an intramembrane cleavage. The resulting cleavage products can be involved in reverse signaling. Presenilins, which constitute the active center of the γ-secretase complex, signal peptide peptidase (SPP), and its homologues, the SPP-like (SPPL) proteases are members of the family of intramembrane-cleaving aspartyl proteases of the GXGD-type. We recently demonstrated that Bri2 (itm2b) is a substrate for regulated intramembrane proteolysis by SPPL2a and SPPL2b. Intramembrane cleavage of Bri2 is triggered by an initial shedding event catalyzed by A Disintegrin and Metalloprotease 10 (ADAM10). Additionally primary sequence determinants within the intracellular domain, the transmembrane domain and the luminal juxtamembrane domain are required for efficient cleavage of Bri2 by SPPL2b. Using mutagenesis and circular dichroism spectroscopy we now demonstrate that a high α-helical content of the Bri2 transmembrane domain (TMD) reduces cleavage efficiency of Bri2 by SPPL2b, while the presence of a GXXXG dimerization motif influences the intramembrane cleavage only to a minor extent. Surprisingly, only one of the four conserved intramembrane glycine residues significantly affects the secondary structure of the Bri2 TMD and thereby its intramembrane cleavage. Other glycine residues do not influence the α-helical content of the transmembrane domain nor its intramembrane processing.
  Journal of Biological Chemistry 12/2011; 287(7):5156-63. · 4.77 Impact Factor
• Article: Intramembrane proteolysis of GXGD-type aspartyl proteases is slowed by a familial Alzheimer disease-like mutation.

  Regina Fluhrer, Akio Fukumori, Lucas Martin, Gudula Grammer, Martina Haug-Kröper, Bärbel Klier, Edith Winkler, Elisabeth Kremmer, Margaret M Condron, David B Teplow, Harald Steiner, Christian Haass
  [show abstract] [hide abstract]
  ABSTRACT: More than 150 familial Alzheimer disease (FAD)-associated missense mutations in presenilins (PS1 and PS2), the catalytic subunit of the gamma-secretase complex, cause aberrant amyloid beta-peptide (Abeta) production, by increasing the relative production of the highly amyloidogenic 42-amino acid variant. The molecular mechanism behind this pathological activity is unclear, and different possibilities ranging from a gain of function to a loss of function have been discussed. gamma-Secretase, signal peptide peptidase (SPP) and SPP-like proteases (SPPLs) belong to the same family of GXGD-type intramembrane cleaving aspartyl proteases and share several functional similarities. We have introduced the FAD-associated PS1 G384A mutation, which occurs within the highly conserved GXGD motif of PS1 right next to the catalytically critical aspartate residue, into the corresponding GXGD motif of the signal peptide peptidase-like 2b (SPPL2b). Compared with wild-type SPPL2b, mutant SPPL2b slowed intramembrane proteolysis of tumor necrosis factor alpha and caused a relative increase of longer intracellular cleavage products. Because the N termini of the secreted counterparts remain unchanged, the mutation selectively affects the liberation of the intracellular processing products. In vitro experiments demonstrate that the apparent accumulation of longer intracellular cleavage products is the result of slowed sequential intramembrane cleavage. The longer cleavage products are still converted to shorter peptides, however only after prolonged incubation time. This suggests that FAD-associated PS mutation may also result in reduced intramembrane cleavage of beta-amyloid precursor protein (betaAPP). Indeed, in vitro experiments demonstrate slowed intramembrane proteolysis by gamma-secretase containing PS1 with the G384A mutation. As compared with wild-type PS1, the mutation selectively slowed Abeta40 production, whereas Abeta42 generation remained unaffected. Thus, the PS1 G384A mutation causes a selective loss of function by slowing the processing pathway leading to the benign Abeta40.
  Journal of Biological Chemistry 10/2008; 283(44):30121-8. · 4.77 Impact Factor
• Article: A gamma-secretase-like intramembrane cleavage of TNFalpha by the GxGD aspartyl protease SPPL2b.

  Regina Fluhrer, Gudula Grammer, Lars Israel, Margaret M Condron, Christof Haffner, Elena Friedmann, Claudia Böhland, Axel Imhof, Bruno Martoglio, David B Teplow, Christian Haass
  [show abstract] [hide abstract]
  ABSTRACT: Gamma-secretase and signal peptide peptidase (SPP) are unusual GxGD aspartyl proteases, which mediate intramembrane proteolysis. In addition to SPP, a family of SPP-like proteins (SPPLs) of unknown function has been identified. We demonstrate that SPPL2b utilizes multiple intramembrane cleavages to liberate the intracellular domain of tumor necrosis factor alpha (TNFalpha) into the cytosol and the carboxy-terminal counterpart into the extracellular space. These findings suggest common principles for regulated intramembrane proteolysis by GxGD aspartyl proteases.
  Nature Cell Biology 09/2006; 8(8):894-6. · 19.49 Impact Factor
• Article: A -secretase-like intramembrane cleavage of TNF by the GxGD aspartyl protease SPPL2b

  Regina Fluhrer, Gudula Grammer, Lars Israel, Margaret M. Condron, Christof Haffner, Elena Friedmann, Claudia B|[ouml]|hland, Axel Imhof, Bruno Martoglio, David B. Teplow, Christian Haass
  Nature Cell Biology 07/2006; 8(8):894-896. · 19.49 Impact Factor