sentence: We propose that the helical Proteobacterium H. pylori uses different mechanisms than C. crescentus and V. cholerae to maintain the even higher levels of negative and positive Gaussian curvature required for its helical cell shape ; H. pylori leverages the bactofilin CcmA , which localizes preferentially to the major helical axis area , to promote synthesis at positive Gaussian curvatures on the sidewall and supplements the MreB-associated enhanced synthesis that is enriched at negative Gaussian curvatures ( the minor helical axis ) ( Figure 11C , right ) .