Table 2 ATP hydrolysis rates of the isoforms

From: The Hsp90 isoforms from S. cerevisiae differ in structure, function and client range

Isoform

Hsp82

Hsc82

ATPase (kcat (min−1)) at 30 °C

0.52 ± 0.02

0.65 ± 0.02

with Aha1

11.59 ± 1.05 (≙2229%)

18.63 ± 0.48 (≙2866%)

with Cpr6

1.42 ± 0.07 (≙273%)

1.81 ± 0.08 (≙278%)

with Cdc37

0.24 ± 0.02 (≙46%)

0.37 ± 0.09 (≙57%)

with Sba1

0.38 ± 0.01 (≙73%)

0.57 ± 0.03 (≙88%)

with Sti1

0.06 ± 0.01 (≙12%)

0.06 ± 0.02 (≙9%)

ATPase (kcat (min−1) at 37 °C

1.37 ± 0.02

2.13 ± 0.13

Isoform

6His-Hsp82

6His-Hsc82

ATPase (kcat (min−1)) at 30 °C

0.75 ± 0.06

1.23 ± 0.10

Isoform domain

Hsp82NTD

Hsc82NTD

Affinity for ATP (Kd (µM))

88 ± 14

151 ± 33

Affinity for RD (Kd (nM))

2.7 ± 1.6

2.0 ± 0.8

  1. The ATPase activities of Hsp82 and Hsc82 were measured with an ATP-regenerating system23. The influence of temperature (30 °C versus 37 °C), of 6His-tagging, and of co-chaperones on the ATPases are shown. In addition, affinities for ATP and RD were determined by ITC and Kd values are indicated.
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