Modernismo de pés descalços: Mário de Andrade e a cultura caipira

Depois das "palavras em liberdade" de Pauliceia desvairada, Mário de Andrade inaugurou, nos anos de 1920, uma nova fase de sua obra literária, que correspondia a uma reorientação do próprio Modernismo brasileiro: a busca da "contribuição milionária de todos os erros" (Oswald de Andrade, "Manifesto Pau Brasil"). Contra as regras da gramática e do discurso letrado, procurava-se imitar a "língua errada do povo". No caso de Mário de Andrade, o desejo de estilizar a fala popular resultou no projeto da Gramatiquinha da Língua Brasileira, que tinha no chamado dialeto caipira uma de suas inspirações. O diálogo com a cultura caipira ocorre em momentos centrais da sua produção literária: Macunaíma, Clã do jabuti, Os contos de Belazarte. Estudando a pintura de Tarsila do Amaral, Mário dirá que a sua brasilidade consiste no "caipirismo" das cores e das formas; algo que também se aplica, e mais radicalmente, à literatura cada vez mais enraizada de Mário de Andrade, na qual os "erros" de linguagem e a presença de personagens caipiras ou selvagens figuram o deslocamento do Brasil e o do próprio escritor em relação ao processo de modernização.

Redox regulation of the proteasome via S-glutathionylation

The proteasome is a multimeric and multicatalytic intracellular protease responsible for the degradation of proteins involved in cell cycle control, various signaling processes, antigen presentation, and control of protein synthesis. The central catalytic complex of the proteasome is called the 20S core particle. The majority of these are flanked on one or both sides by regulatory units. Most common among these units is the 19S regulatory unit. When coupled to the 19S unit, the complex is termed the asymmetric or symmetric 26S proteasome depending on whether one or both sides are coupled to the 19S unit, respectively. The 26S proteasome recognizes poly-ubiquitinylated substrates targeted for proteolysis. Targeted proteins interact with the 19S unit where they are deubiquitinylated, unfolded, and translocated to the 20S catalytic chamber for degradation. The 26S proteasome is responsible for the degradation of major proteins involved in the regulation of the cellular cycle, antigen presentation and control of protein synthesis. Alternatively, the proteasome is also active when dissociated from regulatory units. This free pool of 20S proteasome is described in yeast to mammalian cells. The free 20S proteasome degrades proteins by a process independent of poly-ubiquitinylation and ATP consumption. Oxidatively modified proteins and other substrates are degraded in this manner. The 20S proteasome comprises two central heptamers (β-rings) where the catalytic sites are located and two external heptamers (α-rings) that are responsible for proteasomal gating. Because the 20S proteasome lacks regulatory units, it is unclear what mechanisms regulate the gating of α-rings between open and closed forms. In the present review, we discuss 20S proteasomal gating modulation through a redox mechanism, namely, S-glutathionylation of cysteine residues located in the α-rings, and the consequence of this post-translational modification on 20S proteasomal function.