1. A hybrid topoisomerase comprising a DNA binding subunit of a type II topoisomerase from a Gram-negative prokaryote and an ATP-hydrolyzing subunit of a type II topoisomerase from S. aureus.
2. The hybrid topoisomerase of claim 1, wherein the Gram-negative prokaryote is selected from Enterobacteriaceae, Pseudomonadaceae, Bacteroides species, Haemophilus species, Helicobacter species, Neisseria species, Campylobacter jejuni, Legionella species, and Moraxella catarrhalis.
3. The hybrid topoisomerase of claim 1, wherein the Gram-negative prokaryote is E. coli.
4. The hybrid topoisomerase of claim 1, wherein the type II topoisomerase DNA binding subunit is GyrA from E. coli.
5. The hybrid topoisomerase of claim 1, wherein the ATP-hydrolyzing subunit is S. aureus GyrB or ParE.
6. The hybrid topoisomerase of claim 1, wherein the hybrid topoisomerase comprises E. coli GyrA and S. aureus GyrB.
7. The hybrid topoisomerase of claim 1, wherein the hybrid topoisomerase comprises E. coli GyrA and S. aureus ParE.
8. A method for assaying topoisomerase activity comprising:
a) providing the hybrid topoisomerase of claim 1; and
b) determining topoisomerase activity.
9. The method of claim 8, further comprising contacting the hybrid topoisomerase with DNA after step a).
10. The method of claim 9, wherein topoisomerase activity is determined by detecting a change in topology of the DNA.
11. The method of claim 10, wherein the change in DNA topology is determined by detecting DNA relaxation, DNA supercoiling, or DNA decatenation.
12. The method of claim 8, wherein topoisomerase activity is determined by detecting ATPase activity.
13. The method of claim 12, wherein ATPase activity is detected by measuring inorganic orthophosphate or adenosine diphosphate.
14. The method of claim 8, wherein the hybrid topoisomerase comprises E. coli GyrA and S. aureus GyrB.
15. The method of claim 8, wherein the hybrid topoisomerase comprises E. coli GyrA and S. aureus ParE.
16. A method for identifying compounds that modulate topoisomerase activity comprising:
a) providing a hybrid topoisomerase comprising a DNA binding subunit from a prokaiyotic type II topoisomerase and an ATP-hydrolyzing subunit from a prokaryotic type II topoisomerase;
b) contacting the hybrid topoisomerase with a test compound; and
c) determining topoisomerase activity, wherein a change in topoisomerase activity in the presence of said compound as compared with topoisomerase activity in the absence of said compound indicates that said compound modulates topoisomerase activity.
17. The method of claim 16, further comprising contacting the hybrid topoisomerase with DNA and a test compound.
18. The method of claim 17, wherein topoisomerase activity is determined by detecting a change in topology of the DNA.
19. The method of claim 18, wherein the change in DNA topology is determined by detecting DNA relaxation, DNA supercoiling, or DNA decatenation.
20. The method of claim 16, wherein topoisomerase activity is determined by detecting ATPase activity.
21. The method of claim 20, wherein ATPase activity is detected by measuring inorganic orthophosphate or adenosine diphosphate.
22. The method of claim 16, further comprising determining if the compound has antibacterial activity.
23. The method of claim 16, wherein the DNA binding subunit is E. coli GyrA and the ATP-hydrolyzing subunit is S. aureus GyrB.
24. The method of claim 16, wherein the DNA binding subunit is E. coli GyrA and the ATP-hydrolyzing subunit is S. aureus ParE.
The claims below are in addition to those above.
All refrences to claim(s) which appear below refer to the numbering after this setence.
1. A hydraulic saildrive apparatus comprising:
an upper unit having an input shaft connected to an engine inside a boat; and
a lower unit having an output shaft including a propeller shaft, a lower portion of the lower unit protruding from the boat’s bottom;
wherein the upper unit is provided with a hydraulic forward and reverse switching clutch for transmitting the rotation direction of the input shaft to the propeller shaft, the clutch being capable of changing the rotation direction between forward and reverse relative to the input shaft.
2. A hydraulic saildrive apparatus according to claim 1 further comprising:
a first hydraulic pump driven by the input shaft, for supplying a working oil and a lubricating oil to the clutch from an oil reservoir; and
a second hydraulic pump driven by the output shaft, for supplying at least lubricating oil to the clutch from an oil reservoir.
3. A hydraulic saildrive apparatus according to claim 2 further comprising:
a second lubricating oil supply path connected to a first lubricating oil supply path for supplying lubricating oil to the clutch by the first hydraulic pump, the second lubricating oil supply path extending from the second hydraulic pump; and
a check valve provided in the second lubricating oil supply path, to prevent flowing of the lubricating oil from the first lubricating oil supply path into the direction of the second hydraulic pump.
4. A hydraulic saildrive apparatus according to claim 2 wherein:
a lubricating oil supply path provided by the first hydraulic pump is branched from a working oil supply path provided by the first hydraulic pump, at a point downstream from the first hydraulic pump;
the second hydraulic pump is provided in a part of the working oil supply path, at a point upstream from the first hydraulic pump;
a first bypass oil path is branched from the working oil supply path, at a point between the first hydraulic pump and the second hydraulic pump, the first bypass oil path being connected to the lubricating oil supply path;
the first bypass oil path includes a first check valve to prevent flowing of the lubricating oil from the lubricating oil supply path provided by the first hydraulic pump into the direction of the second hydraulic pump;
a second bypass oil path is branched from the working oil supply path, at a point between the first hydraulic pump and the second hydraulic pump, the second bypass oil path being connected to the oil reservoir; and
the second bypass oil path includes a second check valve to prevent oil flowing from the working oil supply path into the oil reservoir.