Figure 7
C-terminal truncation renders GFP-XYR11–780 non-responsive to inductive signals. (A) Nuclear recruitment dynamics assessed by quantitative live-cell imaging. In contrast to the full-length GFP-XYR1 (TRAL002), whose concentration in nuclei rapidly increased by a factor of up to eight-fold, the truncated GFP-XYR11–780 (TRAL007) was unable to significantly increase its presence in the nucleus in response to cellulase- and xylanase-inducing carbon sources (1.4 mM sophorose, 25 mM lactose and 1 mM D-xylose). Instead, GFP-XYR11–780 consistently showed nuclear presence comparable to the basal presence of GFP-XYR1 under xyr1-non-inducing conditions (65 mM D-xylose). Error bars show standard deviation (n = 2 from two biological replicates involving two different TRAL007 clones). (B) Representative, inverted fluorescence images showing nuclear import of GFP-XYR1 and GFP-XYR11–780 after one hour of sophorose induction. In contrast to the full-length GFP-XYR1 construct, the truncated version is barely visible inside nuclei before induction (arrows). Most importantly, upon addition of 1.4 mM sophorose, the nuclear signal of GFP-XYR11–780 does increase, however, only to a fraction of the intensity (about 15%) of the GFP-XYR1 construct under identical conditions. Scale bar, 10 μm.