DNA Photodamage

DNA photodamage recognition by RNA polymerase II.

During gene transcription, RNA polymerase (Pol) II encounters obstacles, including lesions in the DNA template. Here, we review a recent structure-function analysis of Pol II transcribing DNA with a bulky photo-lesion in the template strand. The study provided the molecular basis for recognition of a damaged DNA by Pol II, which is the first step in transcription-coupled DNA repair (TCR). The r...

The size of the melanosome and photodamage of DNA.

Our earlier studies have demonstrated that exposure of Caucasoid skin to longwave uv light after the application of psoralens resulted in an increase in the average size of the melanosomes and changes in the distribution pattern of melanosomes within the keratinocytes. The photobiologic mechanism responsible for the changes in the size of melanosomes is still not clear. However, the action spec...

A Supplement to Photodamage

Unidirectional photodamage of pheophytin in photosynthesis

The primary reactions in photosynthesis take place in the reaction centers surrounded by light harvesting complexes (Blankenship, 2002; Diner and Rappaport, 2002; Frank and Brudvig, 2004). There are two types of photosynthetic reaction centers. The type I reaction center has ironsulfur cluster as stable electron acceptor, such as photosystem I complexes, green bacterial and heliobacterial react...

Mechanisms and Treatment of Photoaging and Photodamage

Damage caused by excessive, long-term sun exposure contributes to signs of ageing and is most readily recognizable on our external surface, the skin. The damaging effects of the sun are mainly caused by ultraviolet radiation (UVR) which, on earth, consists of UVA (320 to 400 nm) and UVB (280 to 320 nm). The third type of UV radiation, UVC, also called short‐ wave or ionizing radiation, is absor...