This article has been cited by other articles in PMC. Abstract The initiation of DNA replication in Saccharomyces cerevisiae requires the action of a multisubunit complex of six proteins known as the origin recognition complex ORC. The identification of higher eukaryotic homologs of several ORC components suggests a universal role for this complex in DNA replication.
Epub Dec Apo-bacteriophytochromes modulate bacterial photosynthesis in response to low light.
Bacteriophytochromes BphPs are light-sensing regulatory proteins encoded by photosynthetic and nonphotosynthetic bacteria. This protein class has been characterized structurally, but its biological activities remain relatively unexplored. Two BphPs in the anoxygenic photosynthetic bacterium Rhodopseudomonas palustris, designated regulatory proteins RpBphP2 and RpBphP3, are configured as light-regulated histidine kinases, which initiate a signal transduction system that controls expression of genes for the low light harvesting 4 LH4 antenna complex.
In vitro, RpBphP2 and RpBphP3 respond to light quality by reversible photoconversion, a property that requires the light-absorbing chromophore biliverdin. In vivo, RpBphP2 and RpBphP3 are both required for the expression of the LH4 antenna complex under anaerobic conditions, but biliverdin requires oxygen for its synthesis by heme oxygenase.
On further investigation, we found that the apo-bacteriophytochrome forms of RpBphP2 and RpBphP3 are necessary and sufficient to control LH4 expression in response to light intensity in conjunction with other signal transduction proteins. One possibility is that the system senses a reduced quinone pool generated when light energy is absorbed by bacteriochlorophyll.
The biliverdin-bound forms of the BphPs have the additional property of being able to fine-tune LH4 expression in response to light quality. These observations support the concept that some bacteriophytochromes can function with or without a chromophore and may be involved in regulating physiological processes not directly related to light sensing.Plant Fatty Acid Synthesis Introduction.
Plants synthesise a huge variety of fatty acids although only a few are major and common constituents . Broadly speaking, long-chain fatty acids are synthesised de novo from small precursors ultimately derived from photosynthate.
ARTS. BRUNO CALLORI. THE LION’S BRIDE 4 - 5 SEPTEMBER Gwen Harwood, AO, is regarded as one of our finest poets with a body of work that continues to attract admirers. The process of internalisation begins when important people, such as her father, are merged into the poet’s identity, and is completed through the course of mourning their death.
If the person is unable to mourn, they move into a state of melancholia. Abstract.
T cell activation is initiated by engagement of the T cell receptor (TCR)-CD3 complex by antigen displayed by major histocompatibility complex (MHC) molecules expressed on the surface of an antigen presenting cell (APC).
For an overview of Harwood’s themes and some key poems go to Colleen Keene article Gwen Harwood Selected Poems in The Age (February 11, ). Poetic forms Harwood is interested in . English thus is the only school discipline that has deskilled itself, in that it can now no longer deploy a technical vocabulary to teach English expression and help students diagnose weaknesses.