TY - JOUR
T1 - Calcium regulation of gelsolin and adseverin
T2 - A natural test of the helix latch hypothesis
AU - Lueck, Andreas
AU - Yin, Helen L.
AU - Kwiatkowski, David J.
AU - Allen, Philip G.
PY - 2000/5/9
Y1 - 2000/5/9
N2 - The gelsolin family of actin filament binding proteins have highly homologous structures. Gelsolin and adseverin, also known as scinderin, are the most similar members of this family, with adseverin lacking a C-terminal helix found in gelsolin. This helix has been postulated to serve as a calcium-sensitive latch, keeping gelsolin inactive. To test this hypothesis, we have analyzed the kinetics of severing by gelsolin, adseverin, and a gelsolin truncate which lacks the C-terminal latch. We find that the relationship between severing rate and calcium ion concentration differs between gelsolin and adseverin, and suggest that calcium controls one rate- limiting step in the activation of adseverin and two in the activation of gelsolin. In contrast, both proteins are activated equally by protons, and have identical severing kinetics at pHs below 6.3. The temperature sensitivity of severing by adseverin and gelsolin is remarkably different, with gelsolin increasing its severing rate 8-fold per 10 °C increase in temperature and adseverin increasing its rate only 2-fold per 10 °C increase in temperature. Analysis of the gelsolin construct lacking the C-terminal helix demonstrates that this helix is responsible for the regulatory differences between gelsolin and adseverin. These results support the C- terminal latch hypothesis for the calcium ion activation of gelsolin.
AB - The gelsolin family of actin filament binding proteins have highly homologous structures. Gelsolin and adseverin, also known as scinderin, are the most similar members of this family, with adseverin lacking a C-terminal helix found in gelsolin. This helix has been postulated to serve as a calcium-sensitive latch, keeping gelsolin inactive. To test this hypothesis, we have analyzed the kinetics of severing by gelsolin, adseverin, and a gelsolin truncate which lacks the C-terminal latch. We find that the relationship between severing rate and calcium ion concentration differs between gelsolin and adseverin, and suggest that calcium controls one rate- limiting step in the activation of adseverin and two in the activation of gelsolin. In contrast, both proteins are activated equally by protons, and have identical severing kinetics at pHs below 6.3. The temperature sensitivity of severing by adseverin and gelsolin is remarkably different, with gelsolin increasing its severing rate 8-fold per 10 °C increase in temperature and adseverin increasing its rate only 2-fold per 10 °C increase in temperature. Analysis of the gelsolin construct lacking the C-terminal helix demonstrates that this helix is responsible for the regulatory differences between gelsolin and adseverin. These results support the C- terminal latch hypothesis for the calcium ion activation of gelsolin.
UR - http://www.scopus.com/inward/record.url?scp=0034625120&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=0034625120&partnerID=8YFLogxK
U2 - 10.1021/bi992871v
DO - 10.1021/bi992871v
M3 - Article
C2 - 10819996
AN - SCOPUS:0034625120
SN - 0006-2960
VL - 39
SP - 5274
EP - 5279
JO - Biochemistry
JF - Biochemistry
IS - 18
ER -