Polyhydroxyalkanoate synthase and gene encoding the same enzyme

Details Polyhydroxyalkanoate synthase and gene encoding the same enzyme Polyhydroxyalkanoate synthase and gene encoding the same enzyme

2002-09-30

2004-10-12

Achutamurthy, P. (Department: 1652)

Chemistry: molecular biology and microbiology

Enzyme , proenzyme; compositions thereof; process for...

Oxidoreductase

C435S440000, C435S071100, C435S006120, C435S252300, C435S320100, C536S023200

Reexamination Certificate

active

06803220

ABSTRACT:

BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to a polyhydroxyalkanoate (hereinafter, referred to as a “PHA”) synthase, a gene encoding the PHA synthase, a recombinant vector containing the gene, a transformant capable of expressing the PHA synthase which has been transformed by the recombinant vector, a process for producing the PHA synthase utilizing the transformant, and a process for preparing the PHA utilizing the transformant. In particular, this invention relates to a microorganism-derived PHA synthase capable of producing a polyhydroxyalkanoate and a gene encoding the PHA synthase utilized for expressing the PHA synthase by transformation.
2. Related Background Art
There have been reported a number of microorganisms producing poly-3-hydroxybutyric acid (PHB) or another PHA and storing it therein (“Biodegradable Plastic Handbook”, edited by Biodegradative Plastic Research Society, NTS Co. Ltd., p.178-197). These polymers may be, as conventional plastics, used for producing a variety of products by, for example, melt-processing. Since they are biodegradable, they have an advantage that they can be completely degraded by microorganisms in the natural environment, and they do not cause pollution due to remaining in the natural environment like many conventional polymer compounds. Furthermore, they are excellently biocompatible, and thus are expected to be used in applications such as a medical soft member.
It is known that a composition and a structure of such a PHA produced by a microorganism may considerably vary depending on the type of a microorganism used for the production, a culture-medium composition and culturing conditions. Investigations have been, therefore, mainly focused on controlling such a composition or structure for the purpose of improving physical properties of a PHA.
For example, Japanese Patent Application Laid-Open Nos. 6-15604, 7-14352 and 8-19227 describe that
Alcaligenes eutropus
H16 (ATCC No. 17699) and its variants may produce 3-hydroxybutyric acid (3HB) and its copolymer with 3-hydroxyvaleric acid (3HV) with various composition ratios by changing a carbon source during culturing.
Japanese Patent Publication No. 2642937 discloses that PHA in which a monomer unit is 3-hydroxyalkanoate with 6 to 12 carbon atoms may be produced by supplying a non-cyclic aliphatic hydrocarbon as a carbon source to
Pseudomonas oleovorans
(ATCC No. 29347).
Japanese Patent Application Laid-Open No. 5-74492 discloses methods in which Methylobaterium sp., Paracoccus sp., Alcaligenes sp., and Pseudomonas sp. are contacted with a primary alcohol with 3 to 7 carbon atoms to produce a copolymer of 3HB and 3HV.
Japanese Patent Application Laid-Open Nos. 5-93049 and 7-265065 disclose that
Aeromonas caviae
is cultured using oleic acid or olive oil as a carbon source to produce a two-component copolymer of 3HB and 3-hydroxyhexanoic acid (3HHx).
Japanese Patent Application Laid-Open No. 9-191893 discloses that
Comamonas acidovorans
IF013852 is cultured using gluconic acid and 1,4-butanediol as carbon sources to produce a polyester having 3HB and 4-hydroxybutyric acid as monomer units.
Furthermore, it is reported that certain microorganisms produce PHAs having a variety of substituents such as unsaturated hydrocarbon, ester, aryl (aromatic), and cyans groups, halogenated hydrocarbon and epoxide. Recently, there have been attempts for improving physical properties of a PHA produced by a microorganism using such a procedure. For example, Makromol. Chem., 191, 1957-1965 (1990); Macromolecules, 24, 5256-5260 (1991); and Chirality, 3, 492-494 (1991) describe production of a PHA comprising 3-hydroxy-5-phenylvaleric acid (3HPV) as a monomer unit by
Pseudomonas oleovorans
, where variations in polymer physical properties probably due to the presence of 3HPV were observed.
As described above, microorganism-produced PHAs with various combinations of composition and structure have been obtained by varying factors such as the type of a microorganism used, a culture medium composition and culturing conditions. Each microorganism has an intrinsic PHA synthase with a substrate specificity which is significantly different from others. Thus, it has been difficult to produce PHAs comprising different monomer units suitable to a variety of applications using known microorganisms or PHA synthases in such known microorganisms.
Meanwhile, as described above, a PHA having a variety of substituents in its side chains may be expected to be a “functional polymer” having significantly useful functions and properties owing to the properties of the introduced substituents. It is, therefore, extremely useful and important to search and develop a microorganism which can produce and store a very useful polymer having both such functionality and biodegradability. Furthermore, identification of a PHA synthase involved in production of the highly useful PHA and obtaining a gene encoding the PHA synthase may allow us to produce a novel transformed microorganism capable of producing a desired PHA. That is, constructing a recombinant vector comprising a gene encoding a PHA synthase and providing a microorganism transformed by the recombinant vector may allow us to prepare a PHA using the transformed microorganism or to express a recombinant type of PHA synthase. As described above, it may be important that a transformed microorganism is used to prepare a desired PHA for providing a highly useful tool for improving a productivity for the PHA and for promoting utilization of the PHA.
SUMMARY OF THE INVENTION
Objects of this invention which can solve the above problems are to search a novel microorganism capable of producing and storing in microorganisms a PHA having a novel side-chain structure, to identify an enzyme protein related to the ability of producing the novel PHA, i.e., a novel PHA synthase, and to determine a gene encoding its amino acid sequence. More specifically, an object of the present invention is to provide a novel PHA synthase derived from a microorganism producing a PHA having a novel side chain structure and a DNA encoding its amino acid sequence. Another object of this invention is to provide a recombinant vector to which a DNA encoding an available PHA synthase is introduced and which is used for transformation of a microorganism and a transformed microorganism produced using the recombinant vector. A further object of this invention is to provide a process for expressing and producing a recombinant PHA synthase in the transformed microorganism and a process for preparing a desired PHA using the transformed microorganism.
Still another object of this invention is to provide a modified PHA synthase in which its amino acid sequence is modified as long as an enzyme activity is not affected in expression of the recombinant PHA synthase in the transformed microorganism as described above and a DNA encoding the modified amino acid sequence.
For developing a PHA having a novel side-chain structure useful as, for example, a device material or a medical material aiming at solving the above problems, the inventors have searched a novel microorganism capable of producing and storing the desired PHA therein. Additionally, the inventors have intensely investigated selected novel microorganisms producing a novel PHA for identifying a PHA synthase involved in production of the novel PHA and for obtaining a gene encoding the PHA synthase. Furthermore, the inventors have conducted investigation for constructing a recombinant vector with a gene for the obtained PHA synthase, transforming a host microorganism using the recombinant vector, expressing a recombinant PHA synthase in the transformed microorganism obtained and determining production of the desired PHA.
In the course of the above investigation, the inventors synthesized 5-(4-fluorophenyl) valeric acid (FPVA) represented by formula (II):
and separated from a soil a novel microorganism capable of converting the above compound (II) as a starting material (substrate) into corresponding 3-hydroxy-5-(4-fluorophenyl)val

Affiliated with

Also associated with

Rating

Polyhydroxyalkanoate synthase and gene encoding the same enzyme does not yet have a rating. At this time, there are no reviews or comments for this patent.

If you have personal experience with Polyhydroxyalkanoate synthase and gene encoding the same enzyme, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Polyhydroxyalkanoate synthase and gene encoding the same enzyme will most certainly appreciate the feedback.

Rate now

Comments { 0 }

Profile ID: LFUS-PAI-O-3295914